TX 

ho: 



U. S. DEPARTMENT OF AGRICULTURE. 

OFFICE OF EXPERIMENT STATIONS— BULLETIN NO. 156. 

A. C. TRUE, Director. 



S T V D I E S 



DIGESTIBILITY AND NUTRITIVE VALUE 
BREAD AXD OF MACARONI 



OF 



LMYKliSITY OF MINNESOTA 

1&0&-19Q5. 



HARRY SNYDER, B. S., 

Professor of < 'hemUtry, < 'oUege of Agriculture, Vniversit 
Chemist, AyricuUifral Experiment siat 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 
1905. 




Book ; ;B??$k 



/<*or 



U. S. DEPARTMENT OF AGRICULTURE. 

OFFICE OF EXPERIMENT STATIONS— BULLETIN NO. 156. 

A. C. TRUE, Director. 



STUDIES J ~^ 

OX THE 

DIGESTIBILITY AND NUTRITIVE VALUE OF 
BREAD AND OF MACARONI 

AT THE 

UNIVERSITY OF MINNESOTA 

1903-1905. 



HARRY SNYDER, B. S.. 

Professor of Chemistry, College of Agriculture, University of Minnesota, and 
Chemist, Agricultural Experiment Station. 



WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 
1905. 









jft» * 



\<\*' 



OFFICE OF EXPERIMENT STATIONS. 

A. C. Trie, Ph. D., Director. 

E. W. Allen, Ph. D., Assistant Director and Editor of Experiment Station Record. 
C. F. Langwobthy, Ph. I)., Editor and Expert on Foodsand Animal Production. 

NUTRITION INVESTIGATIONS. 

W. (). Atwatek, I'll. I)., Chief of Nutrition Investigations, Middletown, Qmn. 
C. D. Woods, B. 8., Special Agent <>t Orono, Me. 

F. G. Benedict, Ph. I)., Physiological Cttemist, Middletown, Conn. 
K. D. Milker, Ph. B., Editorial Assistant, MiddleUnon, Conn, 



(2) 



LETTER OF TRANSMITTAL 



U. S. Department of Agriculture, 

Office of Experiment Stations, 

Washington, D. C, May 30, 1905. 

Sir: I have the honor to transmit herewith and recommend for pub- 
lication as a bulletin of this Office, a report of investigations on the 
digestibility and nutritive value of bread, and of macaroni and a 
breakfast food made from American-grown durum wheat, carried on at 
the I Diversity of Minnesota in 1903-1905 by Harry Snvder, professor 
of chemistry in the State University and chemist of the Agricultural 
Experiment Station. The studies are a continuation of the investi- 
gations on the nutritive value of cereal products conducted at the 
University of Minnesota by Professor Snyder and at the Maine 
Agricultural Experiment Station by Prof. Charles D. Woods and 
were undertaken under the same general conditions as the other nutri- 
tion investigations on the food of man conducted under the auspices 
of this Office. ^ 

Thanks are due to the Oklahoma and Oregon experiment stations 
for samples of hard and soft winter wheats, and to the North Dakota 
Experiment Station and the North Dakota Substation for samples of 
durum wheat,- also to the Minnesota Macaroni Company, of St. Paul 
for making the macaroni from specially ground wheat. ' 

The results of the investigations with bread of different sorts are in 
accord with those obtained in former studies, and apparently warrant 
the belief that it may be laid down as a general rule that bread from 
fine patent flours is more thoroughly digestible and so has a mVher 
nutritive value than that from the coarse flours ground from the same 
lots of wheat, although pound for pound it contains somewhat less 
protein and mineral matter. Furthermore, the investigations confirm 
the belief that all flours are quite thoroughly digested, and furnish 
additional proof of the high nutritive value of flour of all grades 
lne experiments with macaroni indicate that this product i. verv 
thoroughly digested, being very similar in this respect to patent flour 
bread, and that the American product made from native durum wheat 
is equal in digestibility and food value to European goods 

Respectfully, A c True? 

Hon. James Wilson, Director, 

Secretary of Agriculture. 

(3) 



CONTENTS. 

Page. 

The Digestibility axd Nutritive Value of Bread 9 

Introduction 9 

Milling the samples of wheat 10 

Description of samples of wheats and rl< >urs 12 

Composition of samples of wheats and flours 13 

Composition of samples of food materials 15 

Composition of feces and urine 16 

Experimental methods 18 

Details of the digestion experiments 21 

Experiments with entire-wheat, straight-grade, and Graham Hours ( bread ) 

from Oregon wheat 21 

Digestion experiment No. 469 21 

Digestion experiment No. 470 22 

Digestion experiment No. 471 23 

Digestion experiment No. 472 24 

Digestion experiment No. 47:1 24 

Digestion experiment No. 474 25 

Digestion experiment X< >. 47o 26 

Digestion experiment Xo. 47H 27 

Digestion experiment No. 477 27 

Experiments with straight-grade, entire-wheat, audi iraham flours i bread) 

from Oklahoma wheat 28 

Digestion experiment No. 478 r 28 

Digestion experiment No. 479 29 

Digestion experiment Xo. 480 30 

Digestion experiment Xo. 481 30 

Digestion experiment No. 482 31 

Digestion experiment Xo. 483 32 

Digestion experiment Xo. 484 33 

Digestion experiment Xo. 485 33 

Digestion experiment Xo. 486 34 

Summary of results obtained with bread from different grades of flour. 35 
Comparison of bread from the three grades of flour from the same lot 

of wheat 36 

Comparison of bread from the same grade of flour from the two lots 

of wheat 38 

Undigested starch in feces 39 

Experiments with bread from ' ' bran flour " 39 

Digestion experiment Xo. 487 40 

Digestion experiment Xo. 488 40 

Digestion experiment Xo. 489 _ _ 41 

Summary of results obtained with bread from bran flour 42 

(5) 



('. 

The Digestibility \m» Nctbitive Value 01 Bread Continued. 

Experiments with bread from " germ flour " 4»> 

I digestion experimenl No. 4!»o 4t; 

Digestion experimenl No. 4!»| 17 

Digestion experimenl No. 492 Ifl 

Summary of result.- obtained \\ ith bread from germ flour 18 

The comparative pecuniary value of Graham, entire-wheat, and straight- 
grade Hour :.(i 

Income and outgo of nitrogen 

I leneral summary of results ami conclusions of experiments with bread. . . M 

The Digestibility and Notbjtive Value of Macaroni 

introduction 

Milling of samples 

Composition of samples of wheal ami milling products .">!• 

Manufacture of the macaroni til 

( !omposition of samples of food materials 81 

Composition of feces and urine 82 

Experimental methods 88 

Details of the digestion experiments (14 

Experiments with macaroni and durum wheat bread <">•"> 

Digestion experiment No. 4'.»:; i,:. 

Digestion experiment No. 4u4 88 

Digestion experiment No. 495 

Digestion experiment No. 4!»f> 87 

Digestion experiment No. 4!i7 

Digestion experiment No. 498 88 

Experiments with macaroni 88 

Digestion experiment No. 592 88 

Digestion experiment No. ."><»:; 70 

Digestion experiment No. 594 71 

Experiments with durum wheat breakfast I' I.. 72 

Digestion experiment No. 595 7l* 

Digestion experiment No. 596 7l' 

Digestion experiment No. ">i»7 . ; 

Summary of digestion experiments with macaroni and durum wheal 

breakfast food 74 

The results of American and other experiment- w ith macaroni 77 

Income and outgo of nitrogen 78 

Conclusions of experiments with macaroni 7U 



ILLUSTRATIONS. 



PLATES. 

Page. 

Plate I. Corrugated rollers of mill 10 

II. Bolting cloth No. 14 (magnified 48 diameters) through which the 

straight-grade flour was passed 12 

III. Oregon and Oklahoma wheats. Fig. 1. — Entire kernels. Fig. 2. — 

Sections of kernels 12 

IV. Experimental flour mill used in the investigations 56 

TEXT FIGURE. 

Fig. 1. General plan of milling system 57 

(7) 



DIGESTIBILITY AND NUTRITIVE VALUE OF BREAD 
AND OF MACARONI. 



THE DIGESTIBILITY AND NUTRITIVE VALUE OF BREAD. 

INTRODUCTION. 

Sonic years ago it was estimated that the amount of wheat consumed 
annually in the United States was 4.."> bushels per capita. 'Phis would 
be equivalent to about 200 pounds of Hour. Later estimates place 
the quantity at 6.23 bushels, which would be equal to 277 pounds of 
flour. Because of its importance no article of food has received more 
attention from investigators during recent years than Hour. In 1897 
an extended series of experiments was undertaken at the Maine and 
the Minnesota experiment stations to determine the digestibility and 
nutritive value of different grades of Hour prepared from the same 
and from different kinds of wheat. Preceding bulletins of this Office 
contain accounts of the results of investigations at the Maine" and 
Minnesota'' stations for 1897 to L902; similar work at the latter station 
for 1903-4 is reported herein. 

The general plan of these investigations has been to prepare the 
three common types of flour — Graham, entire-wheat, and standard 
patent — from the same lot of wheat, and then determine their com- 
parative digestibility and nutritive value by experiments with bread 
made from the flours. As stated in a former report/ Graham Hour is 
unbolted ground wheat; entire-wheat flour contains all of the wheat 
kernel with the exception of a portion of the bran which is removed 
with a coarse screen, while the standard patent, or, as hereafter desig- 
nated, straight-grade, flour contains neither the bran nor the germ, 
but is fine white flour which has passed through a No. 14 bolting cloth 
with 193,211 meshes per square inch. 

The necessity for confining the comparisons to samples prepared 
from the same lot of wheat has also been pointed out."' It is not pos- 
sible to compare accurately the nutritive values of the various types 

«U. S. Dept. Agr., Office of Experiment Stations Buls. 85, 143. 

b U. S. Dept. Agr., Office of Experiment Stations Buls. 67, 101, 126. 

«U. S. Dept. Agr., Office of Experiment Stations Bui. 101, p. 8. 

<*U. S. Dept. Agr., Office of Experiment Stations Buls. 101, p. 6; 126, p. 8. 

(9) 



1(1 

of Hour when each is prepared from :i different lot of wheat, because 
of the wide variations in composition of different kinds of wheats. 
The investigations previously reported have shown that while the 

coarser Hours are somewhat superior as regards the total protein and 
ash present they are inferior as regards digestibility, and that when 
these facts are considered together the advantage from the standpoint 
of nutritive value is with the finer flour. The earlier experiments 
were nia(i(> with wheats from widely different localities, including 
Minnesota northern-grown hard spring wheat. Michigan soft winter 
wheat, Indiana soft winter wheat, Oklahoma hard winter wheat, and 
Oregon soft winter wheat, and it seemed important to determine 
whether similar differences in the composition and digestibility of 
bread from the different kinds of Hour would be noted with Soars 
ground from other types of wheat and whether it was not fair to -a\ 
that the differences observed were characteristic of all wheat-, pro- 
vided Hours were ground from the same sample of grain. The wheats 
selected for the present investigation were Oklahoma hard winter 
wheat and Oregon soft winter wheat secured from the Oklahoma and 
Oregon experiment stations, respectively. These are described in 
detail beyond (p. 12). Portions of each lot were milled into straight 
grade, entire-wheat, and Graham Hour, a- described below, and the 
digestibility and nutritive value of each determined from digestion 
experiments with healthy young men. Furthermore, in order toascer 
tain the influence on completeness of digestion of the bran and the germ, 
generally removed in the milling of white Hour, samples of bran and of 
germ were prepared and added to successive samples of Oklahoma 
straight-grade Hour in about the same amounts as were remo> ed during 
the milling process, and the digestibility and nutritive value of bread 
from these products likewise determined with the same subject-. 

MILLING THE SAMPLES OF WHEAT. 

The wheats used in the experiments previously reported were milled 
in one of the large mills of Minneapolis and in smaller mills in Michi- 
gan and Indiana, where somewhat different systems of milling were 
employed. Although the products of the different systems were of 
the same general character, samples prepared under uniform condi- 
tions afford data for more definite and positive comparisons. Accord- 
ingly, in the present investigation, a mill especially devised for 
experimental purposes, and procured mainly tor these experiment-. 
was used. The mill is provided with four sets of rollers, including 
both corrugated and smooth rollers (illustrated in Plat.- Ii. and has 
the essential features of a patent roller-process mill such as is used in 

huge milling plants. It is supplied with a bolting and sifting attach 
meiit and is, in fact, a roller mill in miniature. Bj it- use it i- possible 



Agr., Bui. 156, Office of Expt. Stations. 




Corrugated Rollers of Mill. 



11 

to prepare straight-grade, Graham, or entire-wheat flours from a small 
sample of wheat. 

The Oregon and Oklahoma wheats were milled under the supervision 
of an experienced miller, and the flour was subjected to the inspection 
of the chief Hour inspector of one of the large milling companies of 
Minneapolis. 

The milling was carried on in the usual way." The screened wheat 
was tirst passed through corrugated rollers to split the wheat kernel 
and flatten the germ. As in ordinary milling it was necessaiy, in 
grinding the samples, to dampen the wheat so as to prevent the bran 
from breaking up into tine pieces and contaminating the straight-grade 
flour. After passing through the second break, small amounts of 
break flour b and granular middlings were separated by means of a tine 
screen and bolting cloths. The stock was removed from the second 
break and the tailings passed on to the third break, which resulted in 
the liberation and reduction of additional quantities of flour and mid- 
dlings, and then on to the fourth break. With each reduction the 
rollers were set a little closer. The granular middlings and stock were 
passed through the smooth rollers three times and finally all brought 
together. All of the straight-grade flour was passed through a No. 1-i 
bolting cloth (illustrated in Plate II) and thoroughly mixed, the bran, 
shorts, germ, and other offals being removed at the different boltings 
from the several breaks. 

This process of milling is known as the gradual reduction process. 
Break flours are tirst produced and then the granular middlings are 
liberated from the tailings and bran and reduced. The second break 
flour is obtained largely from the interior or more floury portions of the 
wheat kernel and is more starchy in character than later break flours. 
The third break flour contains a higher percentage of gluten and other 
proteids than the second break flour. The middlings from the second 
break are more nitrogenous in character than those from the later 
breaks. During the process of milling the break flours become more 
nitrogenous, while the middlings become more starchy in character. 
The different break flours and middlings, with the exception of a small 
amount which is separated as second clear or low-grade flour, are 
finally united, thoroughly mixed and bolted, forming straight-grade 
flour. 

In the milling of these wheats about 70 per cent of the entire wheat 
was obtained as straight-grade flour. In the large mills, where the 

a For a somewhat more detailed account of the milling process, see Minnesota 
Station Bui. 85, pp. 189, 190. 

&In each reduction or "break" the " break flour" is the portion passing through 
the screen and bolting cloths. The "granular middlings" pass through the screen 
but not the final bolting cloth, and are afterwards reduced to flour. The portion not 
passing through the screen is known as the "tailings," and passes on to the next 
" break. " 



12 

otl'al.- are subjected to more exhaustive mining, about 72 per cent of 
straight-grade flour is secured. The milling of tin- samples in the 
laboratory under chemical control has proven un usual h satisfactory, 
as it has enabled the different wheats to be milled and the flours pre- 
pared on a uniform t »:i-~i->. thus rendering the results more valuable. 

DESCRIPTION OF SAMPLES OF WHEATS AND FLOURS. 

A description of the wheats used in this investigation, together with 
the different grades of Hour and milling products made from them, is 
hen- given: 

No. 269. Oregon white winter wheat weighing 60 pounds per nqpshei, grown at 
the Oregon Experiment station, Corvallis, Oreg. See Plate Ml I Director .1 
Withycomhe, of the < Oregon Station, states that this variety of w heat was introduced 
into western Oregon about sixty years ago by the Hudson Bay Company. It is a 
wheal with large white plump starchy kernels. 

No. 271. Graham flour prepared from Oregon wheat. No. 269. Graham flour is 
practically \\ heat meal and consists of the entire wheal kernel, including bran, germ, 
and offal. As no sieves or bolting cloths are used in it- preparation, there are man] 
coarse unpulverized particles present in the product 

No. l'Tl'. Entire-wheat flour from Oregon wheat. No. 269. Entire-wheat flour is 
prepared by removing the larger portion of the coarse bran, while the fine bran, or 
shorts, and germ are retained in the Hour. This was done by the use of coarse wire 

screens. The flour was subjected to two breaks on thecoarseand tw the smooth 

rollers. Entire-wheat Hour is of liner granulation than Graham, hut much co 
than straight-grade Hour. 

No. 273. Straight-grade Hour from Oregon wheat. No. 269. The grain was run 
through three coarse rollers three times, the flour being taken out at each break. 
The middlings were passed through three smooth rollers three times and the Hour 
removed each time. The bran was fairly free from flour. About 70 per c< nt of the 
wheal was recovered as Btraight-grade Hour. 

No. 270. Hard winter Weissenburg wheat weighing 62 pounds per bushel, grown 
at the Oklahoma Experiment station, Stillwater. < >kla. see Plate III.. Director J. 
Fields states that the original seed was obtained through W. T. Swingle, of the 
r. S. Department of Agriculture, and was designated No. 3821. This -ample i- char- 
acteristic of the winter wheat grown in that locality, and in yield comparer- \ery 
favorably with other leading varieties. The kernels were of medium -i/e. amber 
color, and glutinous character. 

No. 274. < rraham Hour from < Iklahoma wheat, No. l'7u. This was prepared in the 
same way as No. 271. 

No. 275. Entire-wheat Hour from Oklahoma wheat. So. 270. This was prepared 
in a manner similar to No. 272, and 86 per cent of the wheat was recovered a- entire- 
wheat Hour. 

No. 276. Straight-grade Hour from Oklahoma wheat. No. 270. This was prepared 
in the same way as N". .7::. About 70 percent of straight-grade flour was 

No. 413. Bran from Oklahoma wheat. No. l'7o. Bran consists of the coarsely 
ground episperm or outer covering of the w heat kernel. The -ample was ground in 
a burr mill and then in a Maerker mill. 

No. ill. Germ from Oklahoma wheat, No. 270. The germ is the undeveloped 
plumule. In the process of straight-grade Hour making it is excluded, becaua 
it i^ fermentable in character, it impairs the keeping qualities <<\ the Hour and pro- 



U. S. Dept. of Agr., Bui 156, Office of Expt. Statioi 





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ri ■ i # 1 1 iff ■ *^ 






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. * ft* a * pii 


M 




_ 


^^^^^^^^^^ 


_ 


J 



Bolting Cloth No. 14 (Magnified 48 Diameters^ Through which the 
Straight-Grade Flour was Passed. 



U. S. Dept. of Agr., BuL 156 Office of Expt Stations. 




Fig. 1 .—Oregon and Oklahoma Wheats. 




Fig. 2.— Oregon and Oklahoma Wheats. 



13 

duces an inferior quality of bread. The sample was ground in the same way as the 
bran. 

No. 415. Bran flour. The sample was prepared by adding 14 per cent of finely 
ground bran (No. 413) to the straight-grade Oklahoma flour (No. 276). 

Xo. 416. Germ flour. The sample was prepared by mixing 93 per cent of straight- 
grade Oklahoma flour (No. 276) with 7 per rent of finely ground germ (No. 414 i. 

COMPOSITION OF SAMPLES OF WHEATS AND FLOURS. 

Complete proximate analyses of all of the wheat and flour samples 
were made according - to the methods recommended by the Association 
of Official Agricultural Chemists." The protein content was calcu- 
lated by the use of two fat-tors, namely, 5.7 and 6.25. Investigations 
have shown that the principal wheat proteids contain about 17.6 per 
cent nitrogen instead of 16 per cent, the value upon which the factor 
6.215 is based, which is commonly used for calculating protein from 
nitrogen. The use of the factor 5.7 gives lower values for the pro- 
tein, but the results undoubtedly represent more nearly the actual 
amount in the wheat than that obtained by the factor 6.25. However, 
for the sake of comparison with investigations previously reported in 
which the factor 6.25 was used, the protein is also computed by the 
use of this factor. The carbohydrates determined by difference are 
also estimated on the basis of protein as computed by both factors. 
The heat of combustion was determined by combustion in a Berthelot- 
Atwater bomb calorimeter, as described in a former publication. 6 In 
the case of the milk samples weighed blocks of cellulose were employed 
to absorb the liquid, according to the method described in a former 
report. '" The calculated heats of combustion of the wheat and flour 
samples were obtained by the use of the following factors: Protein, 
5.9; fat. 9.3; and carbohydrates, 4.2 calories per gram. Earlier inves- 
tigations have shown that when the principal nutrients of wheat flour 
were separated, purified, and burned in the calorimeter they yielded 
the following values per gram: Wheat starch 4.190 calories, wheat fat 
9.282 calories, gliadin 5.924 calories, and glutenin 5.879^ calories. 
The calculated and determined heats of combustion of the flour samples 
agree quite closely, though the agreement is not perfect because of 
the presence of cellulose and other substances which have a factor for 
heat of combustion different from that used in the calculation. 

a U. S. Dept. Agr., Division of Chemistry Bui. 46, revised edition. 
&TJ. S. Dept. Agr., Office of Experiment Stations Bid. 101, p. 10. 
cTJ. S. Dept. Agr., Office of Experiment Stations Bui. 126, p. 9. 
a\J. S. Dept. Agr., Office of Experiment Stations Bui. 101, p. 13. 



14 



Table l. -OomponiUm and heal qfcombtution of wheats and flown. 



Oregon wheal... 

Graham flour 
in .111 No. 269... 

En t irr-u bea i 
flour from No. 



269 

k 1 a ho in a 

Graham flour 

from No. 270... 

Entire-wheat 

flour from No. 
270 



\ 6 2 



Bran 

Germ 

Bran flour.. 

Germ flour. 



16.82 
16.81 

16 63 



15.06 
16.39 

■■ 
16.35 
16.30 



7.62 

6.90 

16.38 
16.16 



13.74 
14.93 
27.24 

13. W 
14.87 






Carbohydratea 
when protein i- 
esdmated as 



81.82 
71 B8 
72.88 



62. 79 

i:.. I.". 
7'.'. Zi 
71. 54 






74.80 
64.26 



1.716 

1.U77 
I 124 



i 110 






Table 1 illustrates the fact that different wheats and different types 

of flour vary widely in composition. Tims, straight-grade flour (No. 
276) prepared from Oklahoma wheat contained a much larger amount 
of protein than Graham flour (No. 271) prepared from Oregon wheat. 
This emphasizes the importance, previously pointed out, of preparing 
the different kinds of flour for investigations of this nature from the 
same lot of wheat. Otherwise, if a straight-grade flour milled from 
one lot of wheat were compared with an entire-wheat (lour milled from 
another and entirely different Lot of wheat, the straight-grade flour 
might contain either more or less starch or protein than the Graham 
flour, according to the character of the wheats from which they were 
prepared. From the data in Table 1 it will he observed, however, 
that for both the Oregon and Oklahoma wheats the Graham flour con- 
tained more protein and fat and less carbohydrates than the entire 
wheat flour, which in turn contained more protein and fat and less 
carbohydrates than the straight-grade flour. 

It will be observed from this table that the Oregon and Oklahoma 
wheats and flours were decidedly unlike in character. The Oregon 
wheat (sample No. 269) was starchy and characterized by a low pro 
tein content, while the Oklahoma wheat (No. 270) was glutinous in char- 
acter and contained a high percentage of protein. The straight-grade 
flour from the Oregon wheat contained 1.47 percent of total nitro- 
gen, 7". l per cent of the proteids being in the form of gliadin soluble 
in 70 per cent alcohol, while the straight-grade flour from the Okla- 
homa wheat contained 2.4J pel cent total nitrogen, of which .".!». 7.~> pel 
cent was in the form of eliadin. 



15 

As pointed out in a former report" the ash content varies so regu- 
larly in different grades of milling products that it is possible to 
determine the grade of flour by determining- the amount of ash which 
it contains. In these samples the ash content of the flour sample 
agrees closely with that known to be present in standard grades of 
straight-grade, entire-wheat, and Graham flour. 

COMPOSITION OF SAMPLES OF FOOD MATERIALS. 



The table below gives the data regarding the composition of the 
foods consumed in the digestion experiments. The values given in 
each case are the result of actual analysis, except that the percentage 
of fat in the dry matter of the flour is used as a basis in the calculations 
for the fat content of bread. The results thus obtained are known to 
be more accurate than those secured from the anal} T sis of the bread, 
because during the process of bread making the fat of the flour is in 
part rendered insoluble. 6 

A sample of 100 grams from each loaf of bread used was dried and 
a composite sample for analysis was then taken proportional to the 
weight of the loaves and the quantity consumed. This has been found 
to be the most satisfactory method of sampling and preparing bread 
for analysis. A composite sample of milk was made for each of the 
digestion trials by reserving 25 cubic centimeters of the mixed milk 
taken at each meal, 100 milligrams of potassium bichromate being used 
as a preservative. 

Table 2. — Composition of bread and milk used in digestion experiments with Oregon and 
Oklahoma wheat breads. 



Kind of material. 



hv -I Ash combus " 



Bread made from: 

Oregon entire-wheat flour 

Oregon straight-grade flour 

Oregon Graham flour 

Oklahoma straight-grade flour 

Oklahoma entire-wheat flour 

Oklahoma Graham flour 

Straight-grade flour with 14<* bran. . 

Straight-grade flour with 7$ germ.. 
Milk, composite sample 



..do.. 
..do.. 



..do.. 



31. 95 

37. 65 
■11.31 
-42. 20 
13. '2d 
38.00 
88.34 
87. 2S 
87.74 
87.92 
87. 53 
sb. ss 
86. 95 
86. 83 



•r rent. 
5.70 
5.41 
6.11 
10.13 
10.60 
10. 65 
9.50 
11.07 
3.62 



3.115 



51.14 
46.11 

44.58 

45. 55 
49. 12 



2. 765 
2.562 
2.783 
2.714 
2. 516 



.75 



aJJ. S. Dept, Agr., Office of Experiment Stations Bui. 101, p. 9. 

&U. S. Dept. Agr., Office of Experiment Stations Bui. 67, p. 45. 

c For explanation of the use of the factor 6.25 for calculation of protein in bread see p. 18. 

d Fat content of dry matter of flour. 

e High ash due to abnormal amount of preservative used in composite sample. 



16 



COMPOSITION OF FECES AND URINE. 

The feces for the experimental period were collected and analyzed 
by the usual methods. The separations of tin- feces al the beginning 
and end <>f each period were effected by means of charcoal in gelatin 
capsules as a marker. The data regarding the composition «»f the 
feces are here tabulated. 



'dry mailer of feces from digestia 
Oklahoma wheat bread. 



\eul* a ,ii, <>,,,,,,, 



Experiment No. 169. 
Experiment No. 17<». 
Experiment No. 171 . 
Experiment No. 47J. 
Experiment No. 473. 
Experiment No. 471. 
Experiment No. 175. 
Experiment No. 47t;. 
Experiment No. -177. 
Experiment No. 478. 
Experiment No. IT'.'. 
Experiment No. 180. 
Experiment NO. 1M. 
Experiment No. 182. 
Experiment No. 183. 
Experiment No. 484. 
Experiment No. 185. 
Experiment No. 486. 
Experiment No. i*7. 
Experiment No. l y >. 
Experiment No. 189. 
Experiment No. 190. 
Ex peri men i No. 191 . 
Experimeni N<>. I'.rj. 



24.05 

22. U 
21.67 

29. 17 



22. 16 

22.30 
30.27 



l; r n nl 






, , 


12.78 






•A 27 


15.80 




1 1 . 26 


11.75 


21.78 


12.64 






11.82 














11.21 


• 






lit 1- 


18. u 


19.61 




11.87 




19.09 






89.12 








- 






18.82 




27.21 






49. 65 










17. yci 




10.87 


15.20 






10.13 




17.09 




8. ".1 




16.06 




11.68 




■ 






11.05 


21.72 












7. I« 


|v ,,« 


22 11 




- 








- 


31.11 






16.19 









I -.1 

1.134 

l.2«l 
1. 804 

I M.i 



The urine of each subject was collected during each experimental 
period, beginning with 7 a. m. of the first day of the experiment and 
ending at 7 a. in. of the first day immediately following the experi- 
ment. Th«' total amount and specific gravity of the urine and the per- 
centage of nitrogen in it were determined for each day. These data 
are here given: 



Table 4. — Amount, specific gravity, and nitrogen of urim from 
uuth Oregon and Oklahoma wheat bread. 



digettio 



i /// i inn nl* 



Sam- 


Sub- 


pie 


ject 


No. 


No. 


27V 


1 


282 


1 




1 


--- 


1 


280 


2 


a 


■1 


- 


■1 


289 


l 



Whence obtained. 



T.,tal 

Vui.lr.l 



Experiment No. 169: Oram*. 

Kir*t day 1. 119 1.028 

Second -lav 972 1.886 

Third 'lav 

Fourth day 1.78 

Experimeni No. 170 

First day tit i (r.»7 

Second day : 

Third (lav 515 1.080 

Fourth day 1.014 l Of) 

iU.8. Dept Agr., Office of Experiment Station* Buls. 21, p H 14 



l 16 

i a 



17 



mint, sjteciric ijrariti/, and nitrogen of urine from digestion experiments 
with Oregon and Oklahoma wheat bread — Continued. 



Sub- 
ject 
No. 



Whence obtained. 



Experiment No. 471: 

First day 

Second day 

Third day 

Fourth day 

Experiment No. 4.'-': 

First day 

Second day 

Third day' 

Fourth day 

Experiment No. 473: 

First day 

Second day 

Third day 

Fourth day 

Experiment No. 474: 

First day 

Second dav 

Third day 

Fourth day 

Experiment No. 475: 

First day 

Second dav 

Third day 

Fourth day 

Experiment No. 476: 

First day 

Second dav 

Third day 

Fourth day 

Experiment No. 477: 

First day 

Second dav 

Third dav 

Fourth day 

Experiment No. 478: 

First day 

Second dav 

Third day' 

Fourth day 

Experiment No. 479: 

First day 

Second dav 

Third dav" 

Fourth dav 

Experiment No. 4*0: 

First day 

Second dav 

Third day'. 

Fourth day 

Experiment No. 481: 

First day 

Second dav 

Third day' 

Fourth day 

Experiment No. 482: 

First day 

Second dav 

Third day". 

Fourth dav 

Experiment No. 483: 

First day 

Second day 

Third day 

Fourth day 

Experiment No. 484: 

First day 

Second day 

Third day 

Fourth day 

Experiment No. 485: 

First day 

Second dav 

2 | Third day". 

2 : Fourth day 

i Experiment No. 486: 

3 \ First day 

3 ■ Second day 

3 Third day 

3 Fourth day 

29604— No. 156—05 



1.028 
1. 027 
1.026 
1,505 1.025 

743 1.025 

714 1.027 

857 1.029 

1,188 1.020 



1,327 
1,592 
1,891 
2,361 



1.024 
1.026 
1.022 
1.022 



1.021 
1.025 
1.025 
1.023 

1.026 
1.029 
1.027 



1.019 
1.022 
1.021 



Table 4. — Amount, specific grtirily, and nitrogen of urim frm 
with Oregon and Oklahoma wheat bread Conti 



digestion > > /» rimentt 



Bam 

e 


Sub 
ject 
No. 


881 

-i 


1 

I 


us", 
388 


2 
2 

•J 


3*3 
386 
389 


i 

3 


896 
401 
|(M 


1 
1 
1 


399 
402 
105 


2 
2 
2 


400 
408 
406 


3 
3 
3 



Total 
'voWed' - » N " r " 1 -'" 



Experiment No 


187: 






Experiment No 
First day .. 








Experiment No 


189: 






Experiment No 


490: 






Experimenl No 


491: 






Experiment No 


192: 




Third day 



1. 196 



1,648 I 
1,612 
1,768 I 



■ i n 



" Compositi' sample. 

EXPERIMENTAL METHODS. 

The method followed in making the digestion experiments was simi- 
lar to that explained in detail in a former bulletin." A simple diet of 
bread and milk was eaten, each material being consumed ad libitum, 
but the amount taken at each meal weighed and recorded. The 
digestibility of the nutrients of the total diet was determined from tin- 
quantity of each in the food and feces. The digestibility of the nutri- 
ents in the bread alone was computed by assuming coefficients of 
digestibility for the nutrients of the milk, as explained beyond. 

The bread was made by the shorl process of fermentation thai is, 
with a large proportion of yeast. Comparatively large amount- of 
salt and water were used in mixing the dough, hut neither milk nor 
shortening. For each experiment two bakings were made, the »ub 
jects preferring bread twenty-four hours old to fresh bread. 

The digestibility of the total diet of bread and milk was calculated 
from the difference between the total nutrients in the food consumed 
and those in the feces.* The digestibility of the bread alone was cal- 

«U. 8. Dept. Agr., Office of Experimenl Stations Bui. 86. 

& It will be observe that, although the factor 5.70 is more nearly correct for tin- 
calculation of the percentage of protein in cereals from the percentage of nitrogen 
determined, the factor H.2"> lias been used in these experiments. The Bame factor 
has been used fur milK protein, in which ease it is correct. The use of this factor 
for cereals also is merely fur convenience in the computations of the digestibility of 
the protein. If different factors were used for the protein of different foods, the 
same differences in factors would have to be observed in estimating protein of 
and this would involve complicated computations, sine.- the coefficient of dig 
bility would V>e the same whichever factor is used, provided the same factor i- and 
for protein of both food anil feces, the factor ti.L'o lias been Qged uniformly for 
convenience. 



19 

oulated. us in former work, by assuming that 97 per cent of the pro- 
tein, 95 per cent of the fat, and 98 per cent of the carbohydrates of 
the milk were digested. These values have been deduced from the 
results of a large number of digestion experiments with both ordinary 
and special diets." The undigested nutrients of the milk, as calcu- 
lated by the use of these factors, subtracted from the total nutrients 
in the feces give the estimated undigested nutrients from bread, and 
these subtracted from the total nutrients of the bread give the digesti- 
ble nutrients in bread. These last divided by the total nutrients in 
the bread and multiplied by 100 give the percentages or coefficients of 
digestibilit}' of bread alone. 

The amounts of energy given for the bread and milk and the total 
feces were determined by multiplying the total weight of each mate- 
rial b3 T its heat of combustion as determined with the bomb calorimeter. 
The proportion of energy in total food estimated to be available to the 
body was found by dividing the energy of the total digested food by 
the energy of the total food. 

In order to estimate the amounts of energy in the feces from bread 
alone, the energy of the feces from food other than bread (in this case 
milk) was computed b\ r means of factors. Previous investigations* 
have shown that the heat of combustion of the nutrients in daily prod- 
ucts are, per gram, as follows: For protein, 5.65 calories; for fat, 9.25 
calories ; and for carbohydrates. 3. 9 calories. By multiplying the weights 
of the nutrients in the feces from food other than bread b} T these factors 
and adding the products an estimated energy value is obtained. It is 
known, however, as pointed out on page 13, that the energy of food 
materials, when estimated by the use of factors, varies somewhat from 
the value obtained by actual combustion in the bomb calorimeter. A 
similar variation is found in the total feces, and undoubtedly would be 
found in the feces from a portion of the diet could a separation be 
effected and the actual heat of combustion determined. In order to 
approximate this latter value as closely as possible, the energ} 7- of the 
total feces was also calculated b} T means of factors. In this case, how- 
ever, since the total feces were made up of the residues from two 
foods — milk and bread — the factors used were those computed b for a 
mixed diet, these values being per gram as follows: Protein, 5.65 calo- 
ries; fat, 9.1 calories, and carbohydrates, 1.15 calories. It was then 
assumed that the difference in values existing between the energy of 
the total feces as thus computed and as actualh T determined is propor- 
tional to the presumed difference in value between the energ}- of the 
feces from food other than bread as computed and the value which 
would be obtained could an actual determination be made. In other 
words, the calculated energy of the total feces is to the determined 

a Connecticut Storrs Station Rpt, 1899, pp. 84-86. 
b Connecticut Storrs Station Ept. 1899, p. 104. 



20 

energy of the total feces as the calculated energy <»t" the feces from food 
other than bread is to ./■. the value desired. For example, in experi- 
ment No. 1:69 tin' computed heal of combustion of the total feces was 
74.". calories, while tin- value obtained in the calorimeter was 7^7 calo 
Hes. The computed heal of combustion of the feces from food other 
than bread was 242 calories. The proportion was therefore as fol 
tows: 745:787=242:*, or a; =257 calories. The heat of combustion of 
the feces from bread alone was found by subtracting this value from 
the determined heat of combustion of the total feces (7^7 calories). 
This result (530 calories) subtracted from the total heal of combustion 
of bread (4.77<> calories) gives the heat of combustion of the estimated 
digestible nutrient- in bread (4,240 calories), which divided by the 
total heat of combustion of bread (4.77o calories) and multiplied by 
100 gives the proportion (88.9 per cent) of the total energy of the 
bread estimated to be contained in the digestible nutrients. 

The value as thus determined, however, doe- not represent the 
energy actually available to the body, since a portion of the energy <>f 
the digested nutrients is lost in the incompletely oxidized material of 
the urine. The proportion of the energy of the total food and of the 
bread alone which was actually available to the body was computed 
as in previous investigations, according to the assumption that the 
amount of the energy lost in the organic matter of the urine was L.95 
calories per gram of digestible protein. Thus in experiment No. W9 
the total amount of energy lost in the urine was found by multiplying 
the digestible protein in total food (401.4 grams) by 1.25, which gave 
502 calories. This product was subtracted from the energy of tin- 
total food digested (!i.7.~>t', calories), and the difference (9,254 calories) 
divided by the energy in the total food (10,543 calories) and multiplied 
by LOO gave the proportion of energy in the total food actually avail- 
able to the body (87.8 percent). The proportion of energy in bread 
alone which was actually available (87 per cent) was obtained in like 
manner by dividing the difference between the estimated energy in 
the bread digested (4.24u calories) and the energy lost in the urine 
(70.9X1.25=89 calories) by tin- total energy in the bread (4.77<> 
calorie-). 

As pointed out in former report-, it is well known that the digestion 
coefficients obtained in the manner described are relative rather than 
absolute. It is believed, however, that while the figures for a -ingle 
digestion experiment may be open to criticism, the results of a series 
of experiments as reported in this bulletin are comparable because 
whatever error is introduced in one experi nt i- common to all. 

Since the determination- of dry matter, nitrogen, and energy are 
known to beof greater accuracy t ha n t he other chemica I data included. 

particular attention is given to the results and conclusions based upon 
these values. 



21 



DETAILS OF THE DIGESTION EXPERIMENTS. 

In these investigations with Oregon and Oklahoma wheats two series 
of digestion experiments were carried on, each series consisting- of 
three experiments with each of three subjects. The diet consisted of 
milk, and bread made from the different grades of Hour. In the first 
series the first three experiments were carried on simultaneously, the 
three subjects being- fed on bread from the entire-wheat flour milled 
from the Oregon wheat, and in addition sufficient milk to make the 
diet palatable. Three more experiments followed in which bread from 
the straight-grade flour was substituted for the entire-wheat bread, and, 
finally, in three more experiments Graham bread was used. In the 
second series the experiments were repeated in a similar way with bread 
made from the Oklahoma wheat. 

Besides these, two additional experiments were made with each sub- 
ject in order to determine the influence of the bran and germ upon the 
completeness of digestion. In the first of these the diet consisted of 
bread from bran flour, eaten with some milk. In the second, bread 
from germ flour was substituted for the bran flour bread. 

The total number of separate experiments was therefore twenty-f our. 
The period of duration in each of the experiments with the ordinary 
flours was four days, or twelve meals; in the experiments with the 
bran and germ flour breads it was three days, or nine meals. 

The subjects, designated in these experiments as Nos." 1, 2, and 3, 
were young men in good health. One was employed as a laborer 
on the university farm at field work and the care of stock, and the 
other two devoted part of their time to university studies with several 
hours each day of miscellaneous muscular work. 

EXPERIMENTS WITH ENTIRE- WHEAT, STRAIGHT-GRADE, AND 
GRAHAM FLOURS (BREAD) FROM OREGON WHEAT. 

The following tables, Nos. 5 to 13, give the data of the nine experi- 
ments in the series with Oregon wheat. Accompanying- each table 
are statistics regarding the diet, subject, and date of the experiment, 
and a summary of the data of income and outgo of nitrogen during 
the experimental period. 

DIGESTION EXPERIMENT NO. 469. 

Kind of food. — Milk, and bread made from Oregon entire- wheat 
flour. 

Subject. — Man No. 1. Farm hand employed at average farm labor. 

lV,/'ght. — At the beginning of the experiment 180 pounds; at the 
close 180 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast, 
March 11, 1903. 



n 



Table 5. Remits of digestion experiment No. ?'•'<. 



Sam- 
P'e 


Weight ol 
material. 


Protein 


Kal. 


Carboh] 
dratet 


ash. 






K 1 consumed: 


1,869.0 

■.'. 1 1 _• ii 


106.0 
840.1 


' 20.8 


i 


64.9 


I.77U 


27a 


Milk 








446.7 


867.2 


1,328.7 


81.1 


10.543 












175.0 


45.3 
10.2 


•j-.v 1 
16 '.' 


67.2 

7.1 


Hi 1 


187 




I-Mimated feees from 1 < « ■< I other 






Estimated feces from bread 












85.1 




60.1 




530 














401.4 


334.8 


1.261.5 
913.8 


41.0 


9,756 




Estimated ditfestihle nutrii'lits 








Coefficients of digestibility of 
















Per cent. 
66. 9 


98. 7 


Per vent. 


Percent 


Percent. 




Estimated coefficients of digesti- 




.. . 




I'roportioii of etien,'\ actually 
available to the body: 



































During this experiment the subject eliminated t,535 prams urine, 
containing' 62.94 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food L7.87 grams; outgo in 
urine 15.74 grams; and in feces L.81 grams; implying a gain of 0.32 
gram nitrogen, corresponding to 2 grams protein. 

DIGESTION EXPERIMENT NO. 470. 

Kvndoffood. — Milk, and bread made from Oregon entire-w heat 
flour. 

Subject.— "Man No. 2. University student employed about two hours 
per dav at miscellaneous manual Labor; walked about 2 miles daily. 

Weight. — At the beginning of the experiment L59.25 pounds; at 
the close 158.5 pounds. 

/Juration. Four days, with twelve meals, beginning with breakfast 

March 11. l!>o: J ,. 

Table 6. — Results of digestion experiment No. ¥70, 



Sam- 




Weightof 

man-rial. 


Protein 


Kal. 


Carbohy- . , 
dratee * " 


Bneigj 


■J77 


F l consumed: 

Bread 


Grams. 
2,628.0 
7,998 


149.5 


Grams. Grams. 
28.6 1,874 2 




27S 


Milk 














09.0 


314. 9 


1.675.7 | 78.0 


11, 637 










292 


176.0 


42.3 
8.7 


16.3 
14.3 


80.6 36.8 



786 




Estimated feces from food other 


221 




Estimated feces from bread 












88.6 




71.6 ... 


564 
















396.7 
116.9 


298.6 


1,696.1 41.2 






Estimated diKestihle nutrient* 



















§3 



Table 6. — Results of digestion experiment No. 470 — Continued. 



pie 
No. 


Weight of 
material. 


(Nxti.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Coefficients of digestibility of 




Per cent. 
90.4 

77.5 


Per cent. 
94. s 


Per cent. 
95.2 

94.6 


Per cent. 


Per cent. 




Estimated coefficients of digesti- 




(91.6) 




Proportion of energy actually 
available to the body: 









































During this experiment the .subject eliminated 3,006 grams urine 
containing 52.65 grams nitrogen. The average nitrogen balance per 
da} T was therefore as follows: Income in food 17.56 grams; outgo in 
urine 13.16 grams; and in feces 1.69 grams; implying a gain of 2.71 
grams nitrogen, corresponding to 16.9 grams protein. 

DIGESTION EXPERIMENT NO. 471. 

Kind of food. — Milk, and bread made from Oregon entire- wheat 
flour. 

Subject. — Man No. 3. University student employed one-third of 
the time at office work, with exercise the same as subject No. 2. 

Weight. — At the beginning of the experiment 158 pounds; at the 
close 155 pounds. 

Duration. — Four days, with twelve meals, beginning with break- 
fast March 11, 1903. 

Table ".—Result* of digestion experiment No. 471. 



Sam- 
ple 
No. 




Weight of 
material. 


Protein 
(NX6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


Grams. 1 Grams. 
1,811.0 ! 103.2 
5,302.4 j 192.0 


Grams. 
19.7 
189.8 


199.9 


Grams. 
15.8 
36.6 






















209.5 


1,148.7 


52.4 
















150.0 


37.9 

5.8 


16.9 
9.5 


62.6 
4.0 


32.6 






Estimated feces from food other 






Estimated feces from bread 












32.1 




58.6 




528 














257.3 
71.1 


192.6 


1,086.1 
890.2 


19.8 






Estimated digestible nutrients 








Coefficients of digestibility of 














Per cent. 

87.2 
68.9 


Per cent. 
91.9 


Per cent. 
94.6 
93.8 


Per cent. 
37.7 


Per cent. 
(91.5) 
(88.6) 

87.4 
86.7 




Estimated coefficients of digesti- 






Proportion of energy actually 
available to the body: 
























1 









24 



Daring this experiment the subject eliminated 2,854 grams urine, 
containing 47.79 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food L1.81 grams; outgo in 
urine L1.95 grams; and in feces L.52 grams; implying a loss of 1.66 
grams nitrogen, corresponding to L0.4 grams protein. 

DIGESTION EXPERIMENT NO. 472. 

Kind of food. — Milk, and bread made from Oregon Btraight-grade' 
flour. 

Subject. — Man No. 1. Conditions as in experiment No. 469. 

Weight. — At the beginning of tin- experiment 171.."' pounds; at tin- 
close 174 pounds. 

Duration. Four days, with twelve meals, beginning with breakfast 
March 26, 1903. 

Table 8. — Results of digestion experiment No 



Sam- 




Weight .. I 

material. 


Protein 


Fat. 


Oarboby- 


A-l. 


Knergy 




Pood <<>nsumed: 


2,544.0 

9, i.t;{. 8 


lirnins. 

187.6 
271.0 


Oram*. 


1. 171.7 


liram*. 
















308 






40*. 


430.9 


L 880.0 


99. * 










117.0 


28.0 

s. 1 


14.8 
JO. 4 


37.0 


37.2 




Estimated feces from food other 


















ly.y 




28.8 






















380.6 
117.7 


416.1 


1.843.0 
1,442.9 


62.6 


13,497 




Estimated digestible nutrient- 




















Coefficients of digestibility of 




Pi r <■< i,l. 
98. 1 


Percent 


/Vr rrnt. 


ft r rml. 


Prr cent. 




Estimated coefficients of digesU- 






Proportion of energy actually 
available to the body: 







































During this experiment the subject eliminated 5,206 grams nrine, 
containing 71.64 grams nitrogen. The average nitrogen balance per 

day was therefore as follow-: Income in food 1 «'..:; 4 grams; outgo in 
urine 17.91 grams; and in feces L. 12 grams; implying a loss of -'.•'•'• , 
grains nitrogen, corresponding to L6.8 grams protein. 

DIGESTION EXPERIMENT NO. 473. 

Kind of food. — Milk, and bread made fr Oregon straight-grade 

flour. 

Subject.- Man No. 2. Conditions as in experiment No. 47<>. 
Weight. At the beginning of the experiment 152.5 pounds; at the 

close 154 pound-. 



25 

Duration. — Four days, with twelve meals, beginning with breakfast 
March 26, 1903. 

Table 9. — Results of digestion experiment Xo. 473. 



Sam- 




Weight of 
material. 


Protein 

(Nx6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


Grams. 
3, 045. 
8,034.0 


Grams. 

164.7 
237.8 


Grams. 
27.1 
358.3 


Grams. 

1,761.5 
358.3 


Grams. 
27.4 
67.5 


Calories. 
8,419 






6,147 












402. 5 


385.4 


2, 119. 8 


94.9 


14, 566 










309 


97.0 


24.6 
7.1 


11.0 

17.9 


27.0 
7.2 


34.4 






Estimated feces from food other 






Estimated feces from bread 












17.5 




19.8 




















377.9 
147. 2 


374.4 


2, 092. 8 
1,741.7 


60.5 






Estimated digestible nutrients 








Coefficients of digestibility of 














Per cent. 
93.9 


Per cent. 

97.2 


Per cent. 

98.7 
98.9 


Per cent. 
63.8 


Per cent. 

(97.4) 
(98.5) 




Estimated roi'iiicientsof digesti- 




Proportion of energy actually 
available to the body: 



































During this experiment the subject eliminated 4,120 grams urine, 
containing 49.07 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 16.10 grams; outgo in 
urine 12.27 grams; and in feces 0.98 gram; implying a gain of 2.85 
grams nitrogen, corresponding to 17.8 grams protein. 

DIGESTION EXPERIMENT NO. 474. 

Kind of food. — Milk, and bread made from Oregon straight-grade 
flour. 

Subject. — Man No. 3. Conditions as in experiment No. 471. 

Weight. — At the beginning of the experiment 155 pounds; at the 
close 155.5 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
March 26, 1903. 

Table 10. — Results of digestion experiment No. 474- 



pie 

No. 




Weight of 
material. 


Protein 
(Nx6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


Grams. 
2,463.0 
6,192.0 


Grams. 
133.2 
183.3 


Grams. 
21.9 
276.2 


Grams. 

1,424.8 

276.2 


Grams. 
22. 2 
52.0 


Calorics. 


295 


Milk 


4,737 










316.5 


298.1 


1,701.0 


74.2 














111.0 


32.4 

5.5 


11.1 
13.8 


37.0 
5.5 


30.5 






Estimated feces from food other 






Estimated fecesf rom bread 
Total amount digested 












26.9 




31.5 


















284.1 


287.0 


1, 664. 


43.7 


11. 078 



■jri 

'I' \m k lit. - Result! of digestion i tperimeni No. P ; Continued. 



.-Hill 




Weight ol 
material. 


Protein 


«" , :;r:;: , : > **■ 


Encrg] 




Estimated digestible nutrients 




106.8 


Grama 






Coefficients of digestibility of 




















i;-t iiiiat«-<l < . .«-tlii i.iil- ol .lie. Mi 








Proportion ol energy actuully 
available to 1 1 1 « - bod) : 








































During this experiment the Bubjeci eliminated 1,288 grains urine, 
containing 51. 71 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 12.66 grams; outgo in 
urine L2.93 grams; and in feces L29 grams; implying a Loss of L56 
grains nitrogen, corresponding to 9.8 grams protein. 

DIGESTION EXPERIMENT NO. 475. 

liumdqfjbod. — Milk, and bread made from Oregon Graham Hour. 

Subject. — Man No. 1. Conditions as in experiment No. 469. 

Weight. — At the beginning of the experiment 174 pounds; at the 
close 174 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
March 30, 1903. 

Table 11. — Results of digestion ■ tperimeni \ 



Sain 




Weight of 
material. 


Protein 


Pat 

- 


Carbon] 
dratea 


Ufa 


Bnem 




Food consumed: 


Grams. 

:;, i:;i 
8,194 


145.0 








312 


Milk. 












864. 6 


:m.7 




118.4 


14, m 










388.2 


87.0 

1. 1 


43.5 
17.9 


188.4 

- : 


69.3 






K>tirnate<l feces from foo.l other 






Estimated feces from bread. 












82. 6 




179.7 




1,540 














267.6 

127.0 


352.2 


2,055.8 


" 






Estimated digestible nutrients 




7,250 




Coefficients of digestibility of 













Percent. 

60.6 


/•. i ,.,,t. 

■ 


91.6 
90, 1 


/'. r ,:„l. 


Perernt. 

• 




K>tilll!itei| eoetlieielitxif cliec-ti 






Proportion of energy actually 
available to the body: 





































27 

During this experiment the subject eliminated 4,011 grams urine*, 
Containing 58.58 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 14. 19 grams; outgo in 
urine 14.65 grams; and in feces 3.48 grams; implying a loss of 3.94 
grams nitrogen, corresponding to 24.6 grams protein. 

DIGESTION EXPERIMENT NO. 476. 

Kind of food. — Milk, and bread made from Oregon Graham flour. 

Subject. — Man No. 2. Conditions as in experiment No. 470. 

Weight. — At the beginning of the experiment 154 pounds; at the 
close 156 pounds. 

Duration. — Four days, with 12 meals, beginning with breakfast 
March 30, 1903. 

Table 12. — Results of digestion experiment No. 476. 



pie 

No. 




Weight of 
material. 


Protein 

(Nx6.25). 


Fat. 


Carbohy- 


Ash. 


Energy. 




Food consumed: 


Grams. 

2, 736. 


drains. 
167.2 
139.7 


Grams. Grams. 
30.6 ! 1,441.3 
344.2 J 420.8 


Grams. 
42.1 
63.2 


Calories. 


















306.9 


374.8 ! 1,862.1 


105. 3 
















30.2 ; 139.8 

17.2 8.4 


56.3 






Estimated feces from food other 




4.2 






Estimated feces from bread 












58.0 




131.4 




















214.7 
109. 2 




49.0 






Estimated digestible nutrients 






1,209.9 






Coefficients of digestibility of 














Per cent. 
79.7 
65.3 


Per cent. 
91.9 


Per cent. 

92.5 
90.9 


Per cent. 
46.5 


Per cent. 
(90.0) 
(85.5) 




Estimated coefficients of digesti- 






Proportion of energy actually 
available to the body: 






























1 









During this experiment the subject eliminated 3,601 grams urine, 
containing 49.41 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 12.28 grams; outgo in 
urine 12.35 grams; and in feces 2.49 grams; implying a loss of 2.56 
grams nitrogen, corresponding to 16 grams protein. 

DIGESTION EXPERIMENT NO. 477. 

Kind of food. — Milk, and bread made from Oregon Graham flour. 

Subject. — Man No. 3. Conditions as in experiment No. 471. 
Weight. — At the beginning of the experiment 154.5 pounds; at the 
close 151.5 pounds. 

Duration. — Four days, with twelve meals, beginning with break- 
fast March 30, 1903. 



Table L3. — Results of digestion < vperimeni A 



Sum 

pie 




Weight of 
material. 


Protein 


Pat 


Carbon; 
dratea. 


A-h. 


Energy. 


311 
312 


!•' I consumed: 

Bread 

Milk 

Total 


Qrams. 
1,663.0 
6,396. i 


Grams. 

113. J 


Grams. 
17.5 


Grams. 
341.0 


Grama 
24.1 


Calories. 
1,004 






Jos 7 


296.6 


i.H.i. i 


75.3 


s. sa 




185.8 


60.2 
3. 1 


22.0 
14.0 


67.7 


35.4 


822 




Kstiliintril feces from food other 






Estimated feces from bread 













.Tfi.8 




60.9 




















148.5 
38.7 


274. 5 


IJ-X..7 

let :< 


39.9 


7,540 




Kstililiiteil ili^i-til.lr Iilltrienl- 






Coefficients of digestibility of 














Per cent. 

71.1 

H).5 


Per mil. 


Per ■■Hi. 








Kst i lilM t e< 1 eocttieiellts of i litest i- 






l'ro|iorlioii of energy actually 

available to the body: 









































During this experiment the subject eliminated 3,502 grams urine, 
containing 49.58 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: [ncome in food 8.35 grams; outgo in 
urine 12.40 grams; and in feces 2.4] grams; implying a loss of 6.46 
grams nitrogen, corresponding to 40.4 grams protein. 

EXPERIMENTS WITH STRAIGHT-GRADE, ENTIRE-WHEAT. AND 
GRAHAM FLOURS (BREAD) FROM OKLAHOMA WHEAT. 

The data of the experiments with bread made from the three grades 
of flour milled from the Oklahoma wheat are given in Tables 14 to 22, 

which follow. 

DIGESTION EXPERIMENT NO. 478. 

Eindoffood. .Milk, and bread made from Oklahoma Btraight-grade 
Hour. 

Subject. Man No. 1. Conditions as in experiment No. 169. 

Weight. — At the beginning of the experiment 173 pounds; at the 
close IT.", pounds. 

Duration. Four days, with twelve meals, beginning with breakfast 
April 8, 1903. 

Table 14. — Results of digestion i vperimeni No. f78. 



Sam- 

$5. 




Weight ol Protein 
material. ■ \ 6.25 


Pat 


Carbohy- 
drates. 


Ash. 


Energy. 


328 


i- i consumed: 


Grams. Grams. 
860. i 
11,626.0 


Grams. 




Grams. 
15.6 


Calories. 




Milk . 
























1 


' 


— 




== 



29 



Table 14. — Remits of digestion experiment X<>. 47S — Continued. 



ft 




Weight of 


Protein 
(N <6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 






Grams. 

182. 


45.3 
10.1 


17.6 
21.4 


Grams. 
10. 8 


Grams. 
48. 5 


Grams. 

879 




Estimated feces from food other 


368 




Estimated feces from bread 












35. 2 




60.4 




















652.2 
325.2 


434.7 


2, 290. 1 
1,759.2 


63.6 






Estimated digestible nutrients 








Coefficients of digestibility of 














Per cent. 
90.2 


Per cent. 
96.3 


Per cent.. 

97.0 
96.7 


Per cent. 
56.7 


Per cent. 




Estimated coefficients of digesti- 




(94.8) 




Proportion of energy actually 
available to the body: 









































During this experiment the subject eliminated 7,171 grams urine 
containing 111.16 grams nitrogen. The average nitrogen balance per 
da}" was therefore as follows: Income in food 27.90 grams; outgo in 
urine 27.79 grams; and in feces 1.81 grams; implying a loss of 1.70 
grams nitrogen, corresponding to 10.6 grams protein. 
DIGESTION EXPERIMENT NO. 479. 

Kind of food. — Milk, and bread made from Oklahoma straight-grade 
flour. 

Subject. — Man No. 2. Conditions as in experiment No. 470. 

Weight. — At the beginning of the experiment 156 pounds; at the 
close 162 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
April 8, 1903. 

Table 15. — Results of digestion experiment No. 479. 



Sam- 
ple 
No. 




Weight of 
material. 


Protein 
(N x 6.25). 


Fat, 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


Grams. 
2, 673. 
7, 513. 


Grams. 

270. 8 
217. 9 


17."i 
277. 2 


Grams. 

1,367.0 
350. 1 


Grams. 
11.7 
62.4 


Calories. 


















488.7 


294.3 


1,717.1 ! 74.1 


















7.5 
13.9 








Estimated feces from food other 




6.5 


7.0 








Estimated feces from bread 
















24.4 




189 














460. 3 
248. 9 


286.8 


1,685.7 
1,342.6 






Estimated digestible nutrients 






7,250 




Coefficients of digestibility of 












Per cent. 
94.2 
91.9 


Per cent. 
97.4 


Per cent. 
98.2 
98.2 


Per cent. 
58.6 


Per cent. 
(96.7) 
(97.5) 




Estimated coefficients of digest- 






Proportion of energy actually 
available to the body: 







































30 



During this experiment the subject eliminated 4,995 grams urine, 
containing Tit. 77 grams nitrogen. Tin- average nitrogen balance per 
day was therefore as follows: Income in l'< ><><! 19.55 grams; outgo in 
urine 1!».!'4 grams; and in feces 1.14 grains; implying a Loss of L.5S 
grams nitrogen, corresponding to 9.6 grams protein. 

DIGESTION EXPERIMENT NO. 480. 

Kindoffood — Milk, and bread made from Oklahoma straight-grade 
flour. 

Subject. Man No. 3. Conditions as in experiment No. 471. 

Weight. — At the beginning of the experiment L52 pounds: :ti the 
close 152 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
April 8, 1903. 

Table Hi. — Results of digestion experiment No. fSO. 



Sam- 




Weight of Protein 
material. 


Put. 


Carbohy- 
drates. 


Aah. 


Bnergj 




Food consumed : 


Grams. 
2,549.0 
6,961.0 


Grams. 
258. J 
201.9 


Grams. 
16.8 
266. 9 


Grama 

1 . 303. 5 

824. 1 


Grams. 

u.a 

" - 


( nhirim. 






i 174 










Total 




160. 1 


•m. 2 


1.627.9 


69. 


U.M8 






104.0 


30.8 
6.0 


14.4 
12.8 


31.0 
6. 5 


28.3 






Estimated feces from food other 






Estimated feces fnun bread 










24.3 




24.5 




361 












429. X 
238. 9 


258. 8 


1.596.9 
1.279.0 


40.7 






Estimated digestible nutrients 








Coefficients of digestibility of 














/v r ct at. 
08. I 
90.6 


/•< r a hi. 
94.7 


Per ii hi. 
98. 1 
98. l 


Per cent. 
59.0 


Per cent. 




Estimated coefficients of digest- 






Projiortion of energy actually 
available to the body: 




















99 I 













During- this experiment the subject eliminated 4,558 grams urine, 
containing 63.56 grams nitrogen. The average nitrogen balance per 
day was therefore as follow-: Income in food L8.40 grams; outgo in 
urine 15.89 grams; and in feces L.21 grams; implying a gain of L.30 

grams nitrogen, corresponding to s . 1 grams protein. 

DIGESTION EXPERIMENT NO. 481. 

Kind of food. — Milk, and bread made from Oklahoma entire-wheat 
Hour. 

Subject. — Man No. I. Conditions as in experiment No. 169. 

Weight. — At the beginning of flu 1 experiment 174 pounds; at the 
close 17:;. 7.". pound-. 



31 



Duration. — Four days, with twelve meals, beginning with bre 

April 15, 1903. 

Table 17. — Results of <lii/tsti<»i ,.i /nrimtiit Xo. 481. 



ikfast 



Sam- 
ple 


Weight of 

material. 


Protein 
( N ■ 6.25). 


Fat. 


Carbohy- 
drates! 


Ash. 


Energy. 


345 

346 


Food consumed: ' Grams. 

Bread 3, 597. 

Milk 11,569.0 


381.3 

332.0 


37^ 4 
197. 5 


iSae 


8L0 


9, 762 
8, 203 




Total 


713. 3 


534.9 


2.190.7 


114.8 










359 




102. 5 
10.0 


24.7 
24. 9 


182. 8 
10. 6 


59.0 






Kstimated fee.es from food other 
















92.5 


172. 2 


















610.8 
288. S 


510. 2 


2, 007. 9 
1,486.4 


55. 8 






Estimated digestible nutrient. 












Coefficients of digestibility of 


Per a nt. 
85. 6 

,,, 


95.4 


Per cent. 

91.7 
89. (i 


Per cent. 

48. 6 






Estimated eoeMieients of digest!- 1 


(85.6) 




Proportion of energy actually 
available to the bodv: 



























During- this experiment the subject eliminated 6,030 grams urine, 
containing- 9B.61 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 28.53 grams; outgo in 
urine 24.15 grams; and in feces 4.10 grams; implying again of 0.28 
gram nitrogen, corresponding to 1.8 grams protein. 

DIGESTION EXPERIMENT NO. 482. 
Kind of food. — Milk, and bread made from Oklahoma entire-wheat 
flour. 

Subject. — Man No. 2. Conditions as in experiment No. 470. 
Weight. — At the beginning of the experiment 155.5 pounds; at the 
close 155 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
April 15, 1903. 

Table 18. — Results of digestion experiment No. 482. 



pie 
No. 




Weight of 
material. 


Protein 
(NX6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


Grams. 
2,449.0 
7,730.0 


Grams. 
259.6 
221.9 


Grains. 
25.5 
332.4 


Grams. 

1,129.2 

355.6 


Grams. 
23.0 

54.1 


( 'alories. 




Milk 














481.5 




















193.5 


47.2 
6.7 


14. 4 97. 3 
16.6 7.1 


34.6 






Estimated feces from food other 


















40.5 


...| 90.2 






















42.5 






Estimated digestible nutrients 




219.1 




1,039.0 


6,021 















32 



Table 18. — Results of digestion exper in u I mtinned. 



*■"»' -i,t..f Protein 
{:'// material. 


Carboby- 






Coefficients of digestibility oi 










lMimat«-<l< fti«-ient-i.i 






I'r<>i».rti<>ii of enenry actually 
available i<> the body: 





































During tlii- experiment the subject eliminated 3,604 grama urine, 
containing 67.26 grams nitrogen. The average nitrogen balance |>«-r 
day was therefore as follows: Income in fond L9.26 grams; outgo in 
urine 16.82 grams; and in feces 1.89 grams; implying a gain of 0.55 
gram nitrogen, corresponding to 3.4 grams protein. 

DIGESTION EXPERIMENT NO. 483. 

Etnd of food.— Milk, and bread made from Oklahoma entire-wheat 
flour. 

Subject. — .Man No. '■'>. Conditions as in experiment No. 471. 

Weight. — At the beginning of the experiment 154.5 pounds; at the 
close L51.5 pounds. 

Duration. -Fourdays, withtwelve meals, beginning with breakfast 
April L5, 1903. 

Table I.9.— Results of digestion experiment A 



.-am- 
ple 
No. 




Weight «.f 
material. 


Protein 


Fat. 


Carbohy- 
drates. 


Ash. 




Pood consumed: 


Grams. 


■ 


- 
86L5 


798. 1 






Milk 

Total 










41H.1 


369.5 


1,174.1 


73.5 10,498 













193.5 


46.2 
7.0 


20.1 
17.6 


87.4 
7.5 






Estimated feces from food other 

















39.2 




79.9 


626 
















371.9 
144.3 


349.4 


1,086.7 


33.7 9,620 




Estimated riigestiMe nutrients 








Coefficients oi digestibility of 
















/•crcent. 


Par cm/. 




Estimated coefficiei 








Proportion of energy actually 

available to the body: 






























33 

During- this experiment the subject eliminated 6,266 grams urine, 
containing 60.17 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 16.72 grams; outgo in 
mine 15.04 grams; and in feces 1.85 grams; implying a loss of 0.17 
gram nitrogen, corresponding to 1.1 grams protein. 

DIGESTION EXPERIMENT NO. 484. 

Kind of food. — Milk, and bread made from Oklahoma Graham flour. 

Subject. — Man No. 1. Conditions as in experiment No. 469. 

Weight. — At the beginning of the experiment 175 pounds; at the 
close 173.75 pounds. 

Duration. — Four da} T s, with twelve meals, beginning with break- 
fast April 20, 1903. 

Table 20.- — Results of dii/extion experiment No. 484- 



Sam- 
ple 
No. 




Weight of Protein 
material. (NX6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


Grams. 
3, 635. 
12,281.0 


Grams. 
387.1 
361.1 


Grams. 

40.7 

719.7 


Grams. 

1, 620. 5 

423. 7 


Grams. 

52.7 
106. 9 


( 'alorirx. 


















748.2 


760. 4 


2, 044. 2 


159. 6 














486. 


111.0 

10.8 


49.2 
36.0 


242. 7 

8.5 


83.1 


2,297 




Estimated feces from food other 




Estimated feces frombread . 












100.2 




234.2 




















637.2 
286.9 


711.2 


1,801.5 
1, 386. 3 


76.5 


15, 321 
7,318 




Estimated digestible nutrients 






Coefficients of digestibility of 












Per cent. 
85.2 
74.1 


Per cent. 


Per cent. 
85.6 


Per cent. 


Per cent. 

(87.0) 
(80. 0) 




Estimated coefficients of digesti- 






Proportion of energy actually 
available to the body: 









































During this experiment the subject eliminated 7,383 grams urine, 
containing 107.46 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 29.93 grams; outgo in 
urine 26.87 grams; and in feces 4.44 grams; implying a loss of 1.38 
grams nitrogen, corresponding to 8.6 grams protein. 

DIGESTION EXPERIMENT NO. 485. 

Kind of food. — Milk, and bread made from Oklahoma Graham flour. 

Subject. — Man No. 2. Conditions as in experiment No. 470. 

Weight. — At the beginning of the experiment 155 pounds; at the 
close 156 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
April 20, 1903. 

29604— No. 156—05 3 



34 



Table 21.— Results of digestion experiment N 



Sam- 




Weight of 
material. 


Protein 


Eat. 


Carbohy- 
drates. 

1,191.2 


lab. 






Food consumed: 


drums. 

2,672.0 


284 6 
212.7 

























•11)7. 3 




1,440.7 


101.7 


11,711 












•J.M.li 


57.1 

i,. 1 


21.6 
21.2 


134.5 
i.0 


40.8 






Estimated free-, from food other 






Estimated trees from bread 












50.7 




129.5 





















■140.2 
233.9 


432.2 


1,306.2 
1,061.7 


60.9 






Estimated ■ I i^.-t il.lc nutrients 


















Coefficients of digestibility of 




I'ir r< at. 
- 
82. 2 


l'i r a til. 


/'- r ii nl. 








Estimated coefficients of digesti- 








Proportion of energy actually 
available to the i>o<ly : 

































During- this experiment the subjed eliminated 3,628 grams urine, 
containing <i5. 53 grams nitrogen. The average nitrogen balance per 
da\ T was therefore as follows: [ncome in food L9. 89 grams; outgo in 
urine 16.38 grams; and in feces 2.28 grams: implying a gain i 
grams nitrogen, corresponding to T.T grams protein. 

DIGESTION EXPERIMENT NO. 486. 

Kind of food. — Milk, and bread made from Oklahoma Graham 

Stibject. — Man No. 3. Conditions as in experiment No. 171. 

Weight. — At the beginning of the experiment 153.5 pounds; 
close 152.5 pounds. 

Duration. — Four days, with twelve meals, beginning with bre 
April 20, 1903. 

Tabi.k 22.— Results of digestion experiment No. 186. 



.f L.23 



ii th. 



pie 
No. 




Weight of 
material. 


Protein 


Fat. 


Carbohy- 
drates. 


Lsh. 






F l consumed 


lira ins. 
1,661.0 


" 176.9 
208. i 


1- e. 


244.6 


-.1.7 




363 


Milk 






















9,070 




Feces i water-free) 

Kstimated feces from food other 




378 


■J 10.0 


49:4 


24.2 


97.9 


38.5 


935 




Estimated feces from bread 




































133.7 


409.9 


887.2 








Kstimated digestible nutrients 








Coefficients of digestibility of 

total food 


















Prr cent 


■ •. 1 





35 



—Results of digestion experiment No. 486 — Continued. 



pie 
8 


WVitrht of 
material. 


Protein 
(N 6.25). 


Fat. 


Carbohy- 
drates! 


Ash. 


Energy. 


Estimated coefficients of digesti- 




Per cent. 


Per cent. 


Per cent. 

ST. 4 


Per cent. 


Per cent. 
(83.6) 

85.1 
79.6 


' Proportion of energy actually 
available to the body: 
































During this experiment the subject eliminated 4,920 grams urine, 
containing 57.99 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 15.41 grams; outgo in 
urine 11.50 grams; and in feces 1.98 grams, implying a loss of 1.07 
grams nitrogen, corresponding to 6.7 grams protein. 

SUMMARY OF RESULTS OBTAINED WITH BREAD FROM DIFFER- 
ENT GRADES OF FDOTJR. 

The results of the experiments showing the digestibility of the nutri- 
ents and availability of the energy of the three grades of flour are 
summarized in the following tables. Table 23 shows the percentages 
for the total food (bread and milk) and Table 21 the values computed 
for bread alone in the manner previously described (p. 18). These 
latter values are of particular interest. 

Table 23. — Digestibility of nutrients and arai/al, Hit)/ of energy of fatal food. 



Experi- 
ment 
No. 


Sub- 
ject 
No. 


Kind of food. 


Protein. 


Fat. 


Carbohy- 
drates. 


Energy. 




1 
2 
3 

1 
2 
3 

1 
2 
3 

1 
2 
3 

1 
2 
3 

1 
2 
S 


Experiment* u-Uh On nun irlnal. 


Per cent. 
89.8 
90.4 
87.2 


Per cent. 
93.7 
94.8 
91.9 


Per cent. 
94.9 

95.2 
94.6 


Per rent. 










do 












89.1 


93. 5 


94.9 












93.1 
93.9 

89.8 


96.6 
97.2 
96.3 


98.0 
98.7 
97.8 




478 


do 


94.1 










92.3 


96.7 


98.2 










475 


79^7 
a 71. 1 


89.0 
91.9 
92.6 


91.6 
92.5 
94.2 










477 


do 












77.6 


91.2 


92.8 






Experiment* mth Oklahoma wheat. 




481 


&5.6 
90.2 


95.4 
96.0 
94.6 


91.7 
93.4 
92.6 






do 




483 


do 












88.3 


95.3 


92.6 


87 2 








478 


94/2 
93.4 


96.3 

97.4 
94.7 


97.0 
98! 1 




479 






480 


do 












93.7 


96.1 


97.8 










484 


85.2 
S8.5 
87. 2 


95! 2 
94.4 


88.1 
90.7 
90.1 




485 


do 




486 


do 


85.1 




87.0 


94.4 


89.6 











a Omitted from average. 



36 



Table 24. — Dit/istihiliti/ nf nutrients and availability of energy of bread alone. 



Expert 

in. in 


Sub- 
ject 


Kind Ol 1" 1. 


Protein. 


Carbohy- 
drates. 


Energy. 






AV/h /•/' mi nls nilli Orriimi wheat. 


I'i r ii nl. 








...do 


















71.1 


•.'i.i 












1 
2 
3 

3 

•-• 
3 

2 

3 

1 
3 


85.6 
B9 i 


•..» ii 


94.8 






96. 8 




.do 












84.9 














..ii..; 
■< 10.5 


90.1 
9Q.9 






do 


















63.0 


91.2 


82.8 




Entire-wheat Hour bread 

do 

do 

Straight-grade flour bread 

do 

do 




■IM 
482 
483 


78. 7 

84. 1 

TV 7 




-I 9 




79.6 


90.5 


83.8 


ITS 
479 
180 


mi. -J 
91.9 
96.6 


96.7 
98. 1 


90.7 




90.9 


97.7 


92.1 




74.1 
B2.2 
75. 6 


85.6 
87. 1 




486 
486 


do 

do 

Average 






77.3 


87.4 


80.6 



COMPARISON OF BREAD FROM THE THREE GRADES OF FLOUR 
FROM THE SAME EOT OF WHEAT. 

In the experiments with Oregon wheat, the figures in Table 24 -how 
striking differences in the digestionof protein of the same flour by the 
different subjects. Thus, subject No. 2 digested 65.3 per cenl of the 
protein of Graham bread, whereas subject No. 3 digested only 40*5 
per cent. The latter figure is considered abnormally low and \» m>t 
included in the average. In the experiments with the entire-wheat 
bread, subject No. 1 digested 66.9 per cent of the protein, and subject 
No. 2 digested 77.5 per cent; and the variation was nearly as wide in 
the experiments with bread from straight grade flour, ranging from 
79.8 per cent with subject No. 3 to 89. 1 per cenl with subject No. 8. 
On the other hand, in the case of the carbohydrates and energy, the 
variations for the different subjects with the same Hour wn-c com- 
paratively small. Notwithstanding the wide range in the digest 
ibility of protein of the same Hour by the different subjects, the results 
are in perfect accord in lids respect, that each subject digested the 
nutrients of the straight-grade flour more thoroughly than those of 



37 



the entire-wheat, and the nutrients of the latter more thoroughly than 
those of tin- Graham flour. Likewise the energy of the straight-grade 

flour was more available than that of entire- wheat or Graham. 

In the experiments with Oklahoma wheat, there were also appre- 
ciable differences in the digestibility of the protein of the entire-wheat 
flour by the different subjects, and the same in the case of the Graham 
flour. The results for the protein of the straight-grade flour were in 
close agreement. As was the case with the Oregon flours, the results 
with the different subjects on the same flour agreed quite closely 
in respect to the digestibility of carbohydrates and the availability 
of energy. Furthermore, with each subject the digestibility of the 
nutrients and the availability of the energy of the different flours was 
in the following order: Straight -grade, entire-wheat, and Graham. 

In brief, then, the flours from both kinds of wheat give the same 
results, namely, the nutrients of the straight-grade flour are more 
digestible than those of the entire-wheat flour, and the latter are more 
digestible than those of the Graham flour. 

This means that, when the three flours compared are ground from 
the same lot of wheat, in actual nutritive value the straight-grade 
flour stands flrst. entire-wheat flour next, and Graham flour last. 
This may be more clearly apparent when the data are summarized in 
the manner shown in the following table: 

Table 25. — Proportion of total and dir/estihle nutrients and total and available energy in 
different grades of Oregon mid Oklahoma jtour us milled. 



Sam- 


1 Protein (Nx6.25). Carbohydrates. 


Energy per gram. 


ple 
No. 


Kind of flour. 

Total. 


Digest- 
ible. 


Total. 


Digest- 
ible. 


Total. 


Avail- 
able. 




Per <■< nt. 


Per cent. Per cent. Per cent. 
5.65 79.48 72.49 
5. 87 80. 35 75. 61 
6.41 : 81.82 80.35 


Calories. 
3.990 
3.900 
3.880 
4.178 
4.159 
4.040 


Calories. 


Trl 


Oregon entire-wheat flour 8.25 

Oregon straight-grade flour 7.55 


3.420 
3.686 


275 
276 


Oklahoma entire-wheat flour 16. 63 

Oklahoma straight-grade flour... 15.06 


13.24 
13.69 


73.05 
73.57 


66.11 

71.88 


3.485 
3.721 



In the case of the Oregon wheat, considering total protein, the Gra- 
ham flour contained 8.97 per cent, the entire-wheat 8.25 per cent, and 
the straight-grade 7.55 per cent; but, considering digestible protein, 
the straight-grade flour contained 6.41 per cent, whereas the Graham 
flour contained only 5.65 per cent. Likewise the total energy per 
gram was 3.990 calories for Graham flour and 3.880 calories for straight- 
grade; but the available energy per gram was 3.686 calories for the 
straight-grade flour and only 3.284 calories for the Graham flour. In 
the case of the Oklahoma wheat also the proportions of total protein 
and energy were largest in the Graham and smallest in the straight- 
grade flour, whereas the proportions of digestible protein and avail- 
able energy were largest in the straight-grade and smallest in the 



38 

Graham Hour. That is, in the Sours from both kinds of wheat the 
relative nutritive values <>t' the three grades, as Bhown by digest- 
ible protein and available energy, were, first, straight-grade and, last, 

( nuliam. 

In this respect the results obtained in these experiments are exactly 
in accord with those obtained in similar investigations with w heal from 
other Localities. This means that from the same quantity of the three 
grades of Hour from the same lot of wheat the body would actually 
obtain more protein and energy from the entire-wheal flour than from 
the Graham, and still more from the straight-grade flour than from 
the entire-wheat Hour. 

In genera] it may be said that the results obtained with the two sorts 
of wheat .studied in the investigation here reported are in accord with 
those obtained in the earlier investigations of tin- series. This fact is 
a confirmation of the belief that the conclusions drawn regarding the 
nutritive value of different sort-> of flour hold good for all varieties of 
wheat, provided the different flour- are ground from the same sample. 

COMPARISON OF BREAD FROM THE SAME GRADE OF FLOUR 
FROM THE TWO LOTS OF WHEAT. 

Certain differences are noticeable in the digestibility of the nutrients 
and availability of the energy of the breads from similar grades of 
flour produced from the two lots of wheat. It will he observed that 
the percentage of digestible carbohydrates and available energy is 
larger, on the average, for each grade of flour from the Oregon wheal 
than for the same grade from the Oklahoma wheat, though the differ- 
ences are not great. With the protein, on the other hand, the differ- 
ences are larger and the conditions are reversed, the digestibility of 
the flours from the Oklahoma wheat being greater than that of the cor- 
responding flours from the Oregon wheat. A- previously noted, the 
flour from the Oregon wheat was comparatively low in protein, whereas 
that from the Oklahoma wheat was high. 

In a former investigation an attempt was made to determine the 
effect upon digestibility of adding wheat starch to u flour relatively 
rich in protein, in order to reduce the proportion of protein. In 
those experiments the difference between the percentage of protein 
in the normal flour and that in the same flour modified by the addi- 
tion of starch was not so large as the difference between the protein 
content of the Oklahoma and that of the Oregon flour used in the 
present experiments. In the former experiments the digestibility of 
protein was lower in the (lour with the increased starch content (i. c, 
reduced protein content) than in the normal flour. Similarly, in the 
present experiments, the protein was less digestible in tin- flour with 

" t . s. Dept Agr., Office of Experiment Btatram Bui. mi. ,,. :,}. 



39 

the lower protein content, the differences in the present instance being 
even more pronounced than those in the earlier experiments. In both 
cases, then, the indications are that the widening* of the ratio of protein 
to starch in the Hour lowers the digestibility of the protein. 

As mentioned before, the differences in digestibility of the carbohy- 
drates of the same grade of flour from the two lots of wheat were 
small, being largest in the case of the entire-wheat and Graham flours. 
In the case of the straight-grade flours 98.2 per cent of the carbohy- 
drates from the Oregon wheat and 97. T per cent from the Oklahoma 
wheat were digested. Since the carbohydrates of wheat flour are com- 
posed largely of starch, it is evident that wheat starch is a highly 
digestible nutrient, and more thoroughly digested in the form of 
straight-grade than in the other flours. The average difference in the 
digestibility of the carbohydrates of the breads made from the Graham 
and straight-grade flours amounts to 8.7 per cent in favor of the 
straight-grade flour. 

UNDIGESTED STARCH IN FECES. 

In former reports it was pointed out that the large particles 
observed in the fecal matter from the Graham and entire-wheat flours 
contained unaltered wheat-starch granules, which had escaped com- 
plete digestion. In the present digestion experiments also, microscopic 
studies showed the presence of unaltered starch grains in the feces 
from the Graham and entire- wheat flours. 

EXPERIMENTS WITH BREAD FROM "BRAN FLOUR." 

As pointed out in the preceding experiments in the present bulletin 
and in similar experiments previously reported, the Graham flour which 
contains the whole of the wheat kernel, including the bran, and is more 
coarsely ground than entire-wheat or standard patent flours, is less 
digestible than either of these two grades. The cause of this differ- 
ence has sometimes been attributed to the coarseness of the branny 
particles. In order to determine what influence bran in a fine state of 
division would have upon the completeness of digestion, three experi- 
ments were made with straight-grade flour to which very finely ground 
bran was added. For convenience this material has been designated 
'•'bran flour. " 

This bran flour was prepared from milling products of Oklahoma 
wheat, described on pages 12 and 13. A quantity of the bran (No. 413) 
was ground in a burr mill and then in a Maerker mill until it was very 
fine. Some of the ground bran was then mixed with straight-grade 
flour (No. 276), the quantity of bran in the mixture (No. 415) being 14 
per cent of the total, which was about the proportion of bran removed 
in milling. Bread was made from this modified flour in the same way 



4(i 



as from the ordinary Hour- (see p. L8), and was used in digestion 
experiments with the Bame Bubjects as in the preceding experiments. 
One experiment was made w ith each subject. The data of the experi- 
ments ate given in Tables 26 to 28, which follow. 

DIGESTION EXPERIMENT NO. 487. 

Kind of food. Milk, and bread made from bran Hour. 

Subject. — Man No. 1. Conditions as in experiment No. [QQ. 
Weight. — At the beginning of the experiment 182 pounds; at the 
close 179.5 pounds. 

Duration. —Three days, with nine meals, beginning with breakfast 
May 23, L903. 

Table 2d.—Retulti of digatio 



Sam- 
to. 


Weight of 
material. 


Protein 


Fat. 


( arbohy- 

• lr.it. - 








Food 'onsumert: 


2,043.0 


194.1 

3O9.0 


17.2 




• 

w.a 






Milk 
















503.1 


453.7 


i . J4y. 4 


109.8 


12. 189 












175.0 


41.8 


23.4 

8 - 


71.8 


38.0 






Estimated feces from iYkmI cither 






Estimated feces from bread 












32.5 
























401.3 
161.6 


430.3 


1,177.6 


71.8 






Estimated digestible butrients 








Coefficients of digestibility of 














Per ''Hi. 

91.7 






ltr mil. 






Estimated coefficients of digesti- 






Proportion of energy actually 

available to the- body: 
























I 












During this experiment the Bubject eliminated 1,473 grams urine, 
containing 65.75 grams nitrogen. The average oitrogen balance per 

day was therefore as follows: Income in f I 26. B3 grams; outgo in 

urine 21.92 grains; and in feces 2.23 grams; implying a gain oi 
grams nitrogen, corresponding to 16.8 gram- protein. 

DIGESTION EXPERIMENT NO. 488. 

Wind of food.— Milk, and bread made from bran Hour. 

Subject. Man No. 2. Conditions as in experiment No. l7o. 

Weight. — At the beginning of the experiment L55 pounds; at tin- 
close 155.5 pounds. 

Duration. Three days, with nine meals, beginning with breakfast 
May 23, L903. 



41 

-Results of digestion experiment No. 48S. 



Sam- 
ple 
No. 




Weight ol 
material. 


Protein 
(N X6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


Grams. 
1,611.0 
5, 220. 


Grams. 

153. 
182.2 


13.5 

257. 4 


7 733.8 
187.9 


Grams. 

14.6 
53.8 


Calories. 
4,026 


















335.2 


270. 9 


921.7 


68.4 














129.5 


29.3 

5.5 


12.9 
12.9 


56.6 
3.7 


30.7 






Estimated feces from food other 






Estimated feces from bread 












23.8 




52.9 




















305.9 
129.2 


258.0 


865. 1 
680.9 


37.7 






Estimated digestible nutrients 








Coefficients of digestibility of 














Per cent. 
91.3 
84.4 


Per cent. 
95.2 


Per cent. 


Per cent. 
55.2 


Per cent. 
(93.4) 
(90.8) 

88.7 




Estimated coefficients of digesti- 






Proportion of energy actually 
available to the body: 






















86.8 



















During this experiment the subject eliminated 3,016 grams urine, 
containing 62.73 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 17.88 grams; outgo in 
urine 20.91 grams; and in feces 1.56 grams; implying a loss of 4.59 
grams nitrogen, corresponding to 28.7 grams protein. 



DIGESTION EXPERIMENT NO. 489. 

Kind of food. — Milk, and bread made from bran flour. 

Subject. — Man No. 3. Conditions as in experiment No. 471. 

Weight. — At the beginning of the experiment 158.5 pounds; at the 
close 156 pounds. 

Duration. — Three days, with nine meals, beginning with breakfast 
May 23, 1903. 

Table 28. — Results of digestion experiment No. 489. 



Sam- 
ple 
No. 




Weight of 
material. 


Protein 

(NX6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


1,558.' 6 
5, 660. 


Grams. 
148.0 
197.5 


Grams. 
13.1 
279.0 


Grams. 
709.7 
203.8 


Grams. 
14.2 
58.3 


Calories. 


380 


Milk 


4,528 










345.5 


292.1 


913.5 


72.5 


8,421 








395 


93.3 


20.8 
5.9 


6.7 
14.0 


44.9 
4.1 


20.9 






Estimated feces from food other 






Estimated feces from bread 












14.9 




40.8 




















324.7 
133.1 


285.4 


868.6 
668.9 


51.6 






Estimated digestible nutrients 



















42 



Table 28. — Remits of digestion experiment No. f89 Continued. 



Sam- 

t. 




Weight ol 
material. 


Protein 


.. Carbohj- 
K "- dratea! 


hah. 






Coefficients of digestibility ol 




'.•I 
go (i 


Percent. 


1',, r.,,1. 








Kstiinntcil ci.ctliciriitsoi'ili^i-vii 








I'roportioii of energy actually 

available to the bodj : 



































During the experiment the subject eliminated 3,023 grams urine, 
containing 47.46 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food L8.43 grams; outgo in 
urine 15.82 grams; and in feces l.il grams; implying a gain of i.;>n 
grams nitrogen, corresponding to 9.4 grams protein. 

SUMMARY OF RESULTS OBTAINED WITH BREAD FROM BRAN 
FLOUR. 

The results of the experiments with bread from bran flour are sum- 
marized in Table 29. For purposes of comparison the table also includes 

the average of experiments with bread made from the same flour with- 
out the bran. 

Table 29. — Digtxlihifitg of nulr'u nts mul urailability >>( energy of bread from straight- 
grade flour with mill without bran. 



ment 
No. 


Sub- 
ft? 


Kind Hi bread. 


* - t ssa 7 ' 




487 
488 
4.S9 


1 
2 

:; 

1 
■1 
■■■■ 


Bread from straiRht-tfrade Hour with bran added 

iln 

do 

Average 


Percent. 

• - 

90.0 






85.9 93.4 




478 


90.2 96.7 

91.9 

90. 


90.7 


479 
480 


do 

do 

Average 






90.9 97.7 


,,, 



In the experiments with the straight-grade flour without the bran 
the results with the three subjects were in very close agreement. In 
the experiments with the same flour pin- bran the results for carbo 
hydrates and energy agreed fairly well, hut subject No. 3* digested 
more of the protein than either of the other subjects, the results for 
these two being close. Subject No. ."> digested practically the same 
proportion of the protein from the Hour with the bran as from that 
without it. but with the other subjects the protein of the bran flour 
was noticeably less digestible than that of th.' straight-grade flour. 
With all three subjects the digestibility of tin- carbohydrates and the 

availability of the energy were lower for the bran flour than for the 
straight -grad. • Hour. 



43 

Considering- the averages of the experiments with both kinds of 
Hour, the digestibility of the bread from the Hour with the bran was. 
for protein 85.9 per cent and for carbohydrates 93.4 per cent, whereas 
that of the bread from the same flour without the bran was, for pro- 
tein 90.9 per cent and for carbohydrates 97.7 per cent. The inference 
from these results is that the addition of the finely ground bran 
decreased the digestibility of the product. 

Though the bran flour contained a larger percentage of protein than 
the flour without the bran, in consequence of its lower digestibility the 
nutritive value of the former was actually less, as will be apparent 
from a comparison of the data summarized in the following table, 
showing the percentages of total and digestible nutrients and the total 
and available energy per gram in both kinds of flour: 

Table 30. — Comparison of total and digestible nutrients and total and available energy in 
the same flour with and without bran. 



Sam- 


Protein (Nx6.25). 


Carbohydrates. 


Energy per gram. 


is. 


Kind of flour. 

Total. 


Digesti- 
ble. 


Total. 


Digesti- 
ble. 


Total. 


Availa- 
ble. 


415 

276 


Pera hi. 
Straight grade flour with bran added . 15. 35 
Straight grade flour without bran 15. 06 


Pa-ant. 
13.19 
13.69 


Percent. 

71. 23 
73. 57 


Percent. 
67.46 


Odorif)-. 
3.876 
4.040 


dories. 
3.395 
3. 721 



There was a larger percentage of total protein and a smaller per- 
centage of total carbohydrates in the Hour with the bran than in that 
without it: but comparing the digestible nutrients it will be observed 
that what little was gained in total amount added by including the 
finely ground bran was more than lost in the decreased digestibility 
due to the addition of the bran, the proportions of digestible nutrients 
and available energy being larger in the flour without the bran added. 
This means that from the same amounts of both kinds of flour the 
body would actually derive more nutrients and energy from the flour 
without the bran in spite of the fact that the amount of protein is 
larger in the flour with the bran added. 

It is interesting to compare the average values for the digestibility 
of Graham and entire-wheat flours, that is, flours normally containing 
more or less coarse bran, with the average results obtained in diges- 
tion experiments with straight-grade patent flour to which finely 
ground bran was added. Such a comparison is made in the following- 
table, which also shows the digestibility of straight-grade flour: 
Table 31. — Nutrients digested from bread from different kinds of flour. 
Kind of flour. 



Pi r cent. \ Per cent. 

Graham flour 77.3 87.4 

Entire-wheat flour 79.6 ! 90.5 

Straight-grade flour with bran added 85. 9 I 93. 4 

Straight-grade flour ! 90.9 j 97.7 



44 

As has been explained, the < rraham flour contained the \\ hole of the 
wheat kernel and was practically wheal meal, and the entire-wheat 
flour contained all of the kernel except the tough outer skin and was 
somewhat more finely ground than the Graham. The bran flour con 
sisted of straight-grade flour that contained neither l. ran nor germ, to 
which was added the same amount of bran that had been removed in 
milling, the bran having been specially ground until it was about as 
fine as it seemed possible to make it. The entire- wheat flour was 
somewhat more digestible than the Graham, and the bran flour was 
more digestible than the ent ire-wheat, but less so than the straight- 
grade Hour. It would seem from these data that the finer grinding of 
the bran increased its digestibility to a certain extent: but apparently 
its defective digestibility is not entirely due to imperfect grinding, 
because even when finely ground, flour containing it was -till leas 
digestible than the flour without the bran, which indicates that bran 
has some inherent property of resisting the digestive juiee-.. That 
is to say. apparently, when bran was in a fine state of division, as in 
these experiments, it not only failed to digesl completely itself, but 
it also prevented the complete digestion of the white Hour with which 
it was associated. 

The question has been studied hy other investigators, and, in gen- 
eral, it may be said that in the majority of cases when the experi- 
mental conditions were uniform the results obtained are in accord with 
those reported here. No attempt is made here to refer to all of this 
work, though the reports of all such experiment- which have been 
found are included in an unpublished bibliography of bread and related 
foods prepared in connection with the nutrition investigations of the 
Department of Agriculture and referred to in a previous publication." 

In a study of the comparative nutritive value of homemade and 
bakers' bread, Alice M. Fittz* found that a LO-cent loaf of bakers" 
whole-wheat bread was a little heavier, but contained a -mailer per- 
centage of protein and energy, than LO-cent loaves of three sorta ol 
bakers' white bread. With bread prepared at home from uniform 
quantities and under uniform condition- less pronounced differences 
were noted in the composition and energy value of whole-wheat and 
ordinary bread-. 

Hutchison* gives results obtained by Goodfellow, showing "that 
the waste in milk is greater by 3 per cent when given along with 
whole-meal bread than when taken alone. This, a- we have -ecu. i- 
the very reverse of the effect exercised by ordinary bread." 

Experiments by Romberg' have shown that a mixture of finely 

"f. s. Dept. Alt.. Rpt. Director Office Experiment Stations 1902, \: -'<>7. 

&Amer. Kitchen Mag., 17 | 1902), p. 139. 

*'F I and the Principles of Dietetics. London: Edward Arnold, 1901, p. 206. 

''Aicli. Byg., 28 (1897), \>. 244. 



45 



ground rye bran and Hour is not so completely absorbed as the flour 
without the bran. A number of digestion experiments were made b} r 
him to determine the comparative digestibility of the different kinds 
and grades of rye flour. The experiments, which are of especial inter- 
est in connection with a discussion of the effect of the presence of bran 
in the flour on the digestibility of bread, are summarized in the table 
below. The data as originally published showed the percentage 
amounts which escaped digestion, but in quoting the results they- have 
been recalculated to show the coefficients of digestibility, so that they 
may be more readily compared with those reported in this bulletin. 

Table 32. — Coefficients of digestibility of different kinds of rye bread. 



Kind of flour used for making bread. 



****»■ 'HST 



Fine light-colored rye flour 95.85 

Fine rye flour containing a little bran 92. 49 

Fine dark-colored rye flour containing considerable bran 86.36 

Rye graham flour mixed with a little fine flour 79.93 

Rye flour ground from entire grain ! 94.22 



95. 85 
91.92 
85.60 
97.59 



From these tests and others made with the different rye milling pro- 
ducts the conclusion was drawn that adding the bran, even if finely 
ground, diminished dig-estibility and that bran can not be so prepared 
by grinding that it is suited for human food. 

Pannwitz." in a stud\' of the nutritive value of different sorts of 
army bread, also reported at length by Plagge and Lebbin, 6 took into 
account the effect of the presence of different proportions of bran on 
digestibility- In these experiments the diet consisted of bread alone. 
The following table summarizes the principal results and, as before, 
the data have been recalculated to show the coefficients of digesti- 
bility instead of the amounts which escaped digestion: 

Table 33. — Coefficients of digestibility of different sorts of bread. 



Kind of flour used for making bread. 



Decorticated rye flour -with 15 per cent bran removed 

Coarse decorticated rye flour with 7.5 per cent bran removed 

Coarse decorticated rye flour with 15 percent bran removed 

Finely ground decorticated rye flour with 10.84 per cent bran removed 
Finely ground undecorticated rye flour with 12.68 per cent bran remov 
Finely ground undecorticated rye flour with 25 percent bran removed 

Fine wheat flour with 30 per cent bran removed 

Finely ground bran 

Coarsely ground rye. no bran removed— ••pumpernickel" 

Entire-rye bread made from crushed gram without previous grinding 



Per cent. 
56.65 
43. 35 

58. 56 
66.38 



The conclusion was reached that the value of flour depended upon 
the amount of bran removed, and that bran, even if ninety ground, was 
not suitable for human food. In the author's opinion, decortication 
before grinding is not necessary provided 15 to 25 per cent of the bran 



zlnaug. Diss., Univ. Berlin, 



b Veroffentl. Mil. Sanitatsw., 1897, No. 12. 



46 

present is removed in milling; and. furthermore, unless \-> peroentof 
the bran is removed, the decorticated grain, either finely or coarsely 
ground, gives a bread of inferior digestibility. 

In a study of the relation of decortication and grinding to digesti- 
bility Lehmann" reports data which have to do with tie- effect of I nan 
on the digestibility of bread. The data are summarized in Table 84. 

Table 34. — < Coefficients of digestibility of diffi r» »' sorts of ''/•< "</. 



Kiml of Hour naed for making bread. 



riiitrsfly jrroiinil .it-curt i<»it. «l ry.- tlour.st.-iniin-tz process, 94 per cent of the grain . 

Finely ground rye Hour, old pron— . 7u |mt cent ol the grain 

KutliiT coarsely ffroiiiifl 'li nieuteri rye Hour. Steinmetz process, 82 |"-r ■•.in of 

tin- grain 

Finely ground rye flour, old process, 62 percent of the grain 

Finely ground commercial rye Hour. 75 per cent of the grain 



-: 71 



In the author's opinion the Hour specially ground by the Steinmetz 
process, which contained not less than \'> per cent of bran, was about 
as digestible as ordinary rye-flour bread when it form- a part of a 
mixed diet, and. in general, he concludes that there was do marked 
and regular difference in the digestibility of flour from which L8 to38 
per cent of the bran was removed, 

Lehmann'8 conclusions are not in accord with the other- cited, and 
it seems fair to say that the consensus of opinion i- unfavorable to 
bran as a constituent of Hour. 

EXPERIMENTS WITH BREAD FROM "GERM FLOUR." 

Experiments similar to those with bran were also made t<> determine 
the influence of the addition of germ to white flour. A -ample of 
germ (No. 114. obtained in milling Hour No. 276) containing 2 
per cent of protein and 11.23 per cent fat was ground in the -anie 
manner as the bran. A mixture, designated a> "germ flour,' 1 was 
then made, containing 93 per cent of Oklahoma straight-grade 
flour (No. 276) and 7 per cent of the finely ground germ, the germ 
being added in about the same proportion as i- removed during the 
milling process. Bread was made from this mixture as previously 
described, and a digestion experiment with each of the three subjects 
of the preceding experiments was conducted in the usual manner. 
The data of these experiments are given in Tables 35 to 37 following. 

DIGESTION EXPERIMENT NO. 490. 

Kind of food. -Milk, and bread made from germ Hour. 
Subject. Man No. i. Conditions as in experiment No. 409. 
Weight. At the beginning of the experiment L80 pounds; at the 
close 17s pounds. 

"An-:,. Byg., I", i L902), p. 177. 



47 



Duration. — Three days, with nine meals, beginning with breakfast 
May 28, 1903. 





Table 35. 


—Results of digestion experiment 


Xo. 490. 






ale 

NO. 


Weight of 
material. 


Protein 
(NX6.26). 


Fat, 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 




Grams. 


Grams. 


Grams. 
27.1 

386.9 


Grams. 

1,176.4 

446. 5 


Grams. 
16.3 
66.7 


Calorics. 










6,671 




Total 










536.4 


414.0 1,622.9 


83.0 


13, 360 



Feces (water-free) 

Estimated feces from food other 
1 than bread 



Estimated feces from bread . 



Total amount digested . 
Estimated digestible nutrien 



Coefficients of digestibility of 

total food 

Estimated coefficients of digesti- 
bility of bread alone 

Proportion of energy actually 
available to the body: 

In total food 

In bread alone 



Per cent. 
92.4 



Per cent. Per cent. 
97.3 
97.0 



12, 701 

6,342 



Per cent. 
56.9 



Per cent. 

(95.1) 
(94.8) 



During this experiment the subject eliminated 4,913 grams urine, 
containing 79.59 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 28.61 grams; outgo in 
urine 26.53 grams; and in feces 2.18 grams; implying a loss of 0.10 
gram nitrogen, corresponding to 0.6 gram protein. 

DIGESTION EXPERIMENT NO. 491. 

Kind of food. — Milk, and bread made from germ flour. 

Subject. — Man No. 2. Conditions as in experiment No. 470. 
Weight. — At the beginning of the experiment 155 pounds; at the 
close 154 pounds. 

Duration. — Three days, with nine meals, beginning with breakfast 
May 28, 1903. ' 

Table 36. — Results of digestion experiment No. 491. 



Sam- 
ple 
No. 


Weight of Protein „ at 
material. (Nx6.25). * al " 


Carbohy- 
drates. 


Ash. 


Energy. 


397 


Food consumed: 


Grams. 
2,139.0 
6, 550. 


Grams. 
236. 8 
199.8 


Grams. 
44.2 
284.9 


Grams. 

1.050.7 

328. 8 


Grams. 
14.6 
49.1 


Calories. 
5,974 


.Milk 




Total 








436.6 


309.1 


1,379.5 ■ 


63.7 


10, 887 










93.0 


27.1. 
6.0 


9.7 
14.3 


28.9 


27.3 






Estimated feces from food other 






Estimated feces from bread 












21.1 




22.4 




















409.5 
215.7 


299.4 


1,350.6 
1,028.3 


36.4 


10,484 




Estimated digestible nutrients 

















4S 



Table 36.— Results of digestion experiment No. 491 — Continued. 



Sam- 
to. 




Weight ol 
material. 


Protein 


«* ( a S£r **. 






Coefficients of digestibility of 




l'i r a nt. 


Percent. Per cent 








KMiin.iti'l i llirii'iitMif ilitfo-ti- 










lYnportinn nf energy Metimlh 

available t<> the body: 







































During this experiment the subject eliminated 2,598 grama urine, 
containing 47.02 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 23.28 grams; outgo in 
urine L5.67 grams; and in feces L 45 grams; implying a gain of 6.16 
grams nitrogen, corresponding to 38.5 grams protein. 

DIGESTION EXPERIMENT NO. 492. 

Kind <>/ food. — Milk, and bread made from germ Sour. 
Subject. Man No. 3. Conditions as in experiment No. 471. 
Weight. — At the beginning of the experiment L52 pounds; at the 

close 152 pounds. 

pm-tithm. — Three da3 r .s, with nine meals, beginning with breakfast 
May 28, 1903. 

Table 37. — Results of rfit/extion exper'nm nt Xo. *'.<:. 



pie 
No. 




Weight of 

material. 


Protein 
(N X 6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


Grams. 
1,760.0 

5, 600. 


Grams. 
198. 7 
170.8 


Grams. 

19.8 

j is..; 


Grams. 
281.1 


Grams. 


Calories. 


















361. 5 


263.4 


1.140.7 












412 


79.0 


22.1 
5.1 


12.8 
12.2 


23.9 
5.6 






Estimated feces from food other 




« 




Est i muted feces from bread 










17.0 




18.3 




















342. 1 
176.7 


250.6 


1,116.8 
841.3 


33.7 


8.731 




Estimated digestible nutrients 






Coefficients of digestibility of 














Per c nt. 

94.0 
91.3 


Per cent. 
05. 1 


Per cent. 
'.'7. B 


Percent. 


Percent. 

(96.1) 

n. i 




Estimated coefficients of digesti- 






Proportion of energy actually 
available to the body: 









































During this experiment the subject eliminated 3,542 grams urine, 
containing 51.71 grams nitrogen. The average nitrogen balance |>«'i- 
day was therefore as follows: Income in food 1 9. 44 grams; outgo in 
urine L7. 24 grams; and in U'r^s l. is grams; implying a gain of L.02 
grams nitrogen, corresponding to 6.4 grams protein. 



49 



SUMMARY OF RESULTS OBTAINED WITH BREAD FROM GERM 
FLOUR. 

The results of the experiments with bread made from the mixture 
of straight-grade flour and ground germ are summarized in the follow- 
ing table. For comparison the results of experiments with bread 
made from the same flour without the germ are also included. 

Table 3S. — Digestibility of nutrients and arailability of energy of bread from straight- 
grade Hour with and without germ. 



Ex peri- 
No. 


Sub- 
K 


Kind of bread. 


***».tesar 


Energy. 




1 
2 
3 

2 
3 


Bread from flour \ 




Per cent. Per cent. 
87.6 ! 97.0 
91.1 97.9 
91.3 97.9 


Per cent. 






















90.0 


97.6 






Bread from flour \ 


vithout o-erm 




4"s 


90. 2 
91.9 
90.6 


96.7 
98.2 












do 












90.9 


97.7 











Subjects Nos. 1 and 2 digested slightly less and subject No. 3 
slightly more protein from the flour with the germ than from that 
without it, the average from the latter flour being practically 1 per 
cent higher. The average for carbohydrates was the same for both 
kinds of flour, and the availability of energy was a trifle higher in 
the flour without the germ, but on the whole the differences in results 
were so small as to be negligible. Apparently, then, the presence of 
the finely ground germ exerts no appreciable influence upon the 
digestibility of the flour. 

The relative nutritive value of the flour with and without the germ 
is illustrated by the data here summarized. 

Table 39. — Comparison of total and digestible nutrients and total and available energy in 
the same flour with and without germ. 



Sam- 
ple 
No. 


Kind of flour. 


Protein 
(Nx6.25). 


Carbohydrates. 


Energy per gram. 


Total. 


Digesti- 
ble. 


Total. 


Digesti- 
ble. 


Total. 


Availa- 
ble. 


416 
276 


Straight-grade flour with germ added.. 
Straight-grade flour without germ 


Per ct. 
16.30 
15.06 


Per ct. 
14.67 

13.69 


Per ct. 
73! 57 


Per ct. 
69.91 

71.88 


Calories. 
3.962 
4.040 


Calories. 
3. 625 
3.721 



As will be seen from the data in Table 1, the proportion of protein 
in the germ is much larger than that in any other milling product 
from the same wheat, being in the sample analyzed nearly twice as 
29604— No. 156—05 4 



50 

large :is in the straight-grade Hour. Accordingly, the mixture of 
genii ui id straight-grade flour containing only 7 per cent <»!' the former 
had an appreciably larger percentage of total protein than the straight- 
grade flour alone L6.30 as compared with 15.06 percent. Since the 
digestibility of the protein in the mixture was nearly the same as that 
in the Hour without the germ, the percentage of digestible protein 
was also larger in the former, being L4. 67 as compared with 13.69 per 
cent. The proportions of total and digestible carbohydrates, <>u the 
other hand, were both larger in the straight-grade Hour alone, and 
their excess was sufficient to make the total and available energy per 
gram also larger in the Hour without the germ. On the whole, then. 
the total nutritive value of the Hour containing the germ i- no greater 
than that without it. 

Under certain circumstances, for example, where bread form- a 
considerable part of the total diet, a Hour with a large protein content 
and a smaller starch content might be advantageous, because the 
proportion of starch to protein in Hour is so large that a deficiency of 
protein might be characteristic of such a diet. The addition of the 
finely ground germ would then be an advantage, because, as shown 
above, the germ is rich in protein, and appreciably increases the protein 
content of the mixture; and the digestibility of the mixture is practi- 
cally equal to that of the Hour without the germ. 

The particular disadvantage in including the germ is the effed it 
has upon the quality of the flour. The ground germ is easily fer- 
mentable and becomes rancid, and when present the Hour doe- not keep 
well. Furthermore, it has been shown that the proteids <>f wheat 
germ are decidedly different in character and composition from wheat 
gluten, and that the agglutinating properties of the germ are poor. A 
loaf from flour containing the germ, though sweeter in taste, is some- 
what smaller in size and less attractive in appearance than one from 
straight-grade flour without the germ. From a practical standpoint, 
however, this latter feature is of much less importance than the poor 
keeping quality of the Hour. 

THE COMPARATIVE PECUNIARY VALUE OF GRAHAM. ENTIRE- 
WHEAT, AND STRAIGHT-GRADE FLOUR. 

While the composition, digestibility, and palatability of a food are 
important factors in determining its value, the cost or comparative 
pecuniary value also requires consideration. Graham and entire- 
wheat Hours are usually sold at a higher price than w hite or ordinary 
bread Hour. Since the white (straight grade) flour contains somewhat 
more digestible nutrients than either Graham or entire-wheat Hour-. 
it will readily be seen that for a given sum of money white flour would 

" Minnesota Station Bui. 83, |>. 527. 



51 



furnish the largest amount of digestible nutrients and available energy. 
At the time of this investigation Hour was selling in the principal mar- 
kets of the Northwestern States at a cost not exceeding $4.50 per bar- 
rel, while entire-wheat and Graham Hour sold in small packages at the 
rate of $6 to §8 per barrel. In some cases much higher prices are 
charged for entire- wheat flour and similar preparations, as noted in 
studies carried on at the Maine Experiment Station." 

In the following table the comparative amounts of digestible nutri- 
ents which, at the prices given above, can be procured for 10 cents in 
the three types of flour milled from the Oklahoma wheat are given: 

Table 40. — Comparative amounts of digestible nutrients obtained for 10 cents in different 
grades of flour. 



Kind of flour. 



Total 
Price per quantity 
pound. , obtain- 
able. 



Protein Oarbohy- 
obtain- dratesob- 
able. tainable. 



Cents. 

White flour 2. 25 

Entire-wheat flour 3. 00 

Graham flour 3.00 



Pounds. Pounds. 

0. 60 3. 16 

.44 2.18 

.43 2.09 



At the prices given 10 cents will purchase 4.4 pounds of white and 
only 3.3 pounds of entire- wheat or Graham flour. The 4.4 pounds of 
white flour contain 1.24 pounds more of available protein and carbo- 
hydrates than 3.3 pounds of Graham costing the same amount of money. 
The 4.4 pounds of white flour contain 1.14 pounds more digestible pro- 
tein and carbohydrates than the 3.3 pounds of entire- wheat flour costing 
the same amount of money. From a pecuniary point of view it is 
evident that the white flour is much the cheaper. 



INCOME AND OUTGO OF NITROGEN. 

Table 41 summarizes data regarding the income of nitrogen in the 
food and the outgo in the feces and urine, as well as the gain or 
loss by the body in the digestion experiments with the different sorts 
of bread reported in the preceding pages. The figures in each case 
represent the average amounts per day. 

a Maine Station Ept. 1899, pp. 92-106. 



52 



■Average daily income and outgo of nitrogen in digestion experiment* Not 











Nitrogi 




Experi 

ment 
No. 


jecl 
No. 


Kind ol food. 


In food. 


In iirin.-. 


in feces. 


<>r 




1 
2 
3 

1 
2 
3 
1 
2 
3 


Oregon wheat 


11.81 
16.84 
16. 10 
12.66 

1 1. 19 
12.28 

- 


15.74 
18.16 
11.96 

17. -Jl 
12.27 
12.98 
14.66 

12. in 


l.M 
1 . ..'.' 

1.12 

1 . 29 

2. 11 




170 
171 
172 
478 
171 
475 
476 
177 


do 

do 

Straighl grade flour bread with milk 

do 

do 

Graham tlmir bread with milk 

do 

do 








Oklahoma wheat. 










478 
179 
4*0 
181 
482 
183 


1 
2 

3 
1 
2 

3 

1 
2 

3 


Straight-grade flour bread with milk 

do 

do 

Kn tin- wheat Hour 1m -ml with milk 

do 

do 


27.90 
19.65 

18. in 

19.26 
16.72 

19.89 

16. 11 


19.94 
24.16 
16.04 

14.80 


La 

1.21 
1.10 

1 II 


1.7ii 
.17 


485 
486 


.l<> 

do 








Bran flow. 












1 
2 
3 




26.83 
17.88 
18. 18 


21.92 
20.91 
16.82 


1.11 










189 


do 


+ 1.50 


















1 
2 
3 




28. 61 

19.44 


17. Jl 


2.1- 

1. 16 
1.18 












...do 











. The amount of nitrogen taken per day varied within rather wide 
limits, and it is noticeable that subject No. 3, in cadi series of tests, 
received considerably less nitrogen than the other two subjects, owing 
to the fact that he ate smaller amounts of food. 

In experiments of a few days' duration it is not absolutely certain 
that the nitrogen of the urine represents that of the diet, though it 
seems probable that such is the case, as is indicated by the fad that 
marked changes in the nitrogen consumed are quickly followed by 
corresponding changes in the amount-- excreted in the urine. In 11 of 
the experiments there was a gain of nitrogen and in 13 a loss. How- 
ever, too much importance should not be attributed to these gains and 
losses, as the experimental periods were shorl and it is probable that 
in all cases nitrogen equilibrium would have been reached with the 
amounts consumed if the period had been longer. Ii is noticeable 
that on an average the feces from the coarser breads contained a larger 
proportion of the nitrogen consumed than was the case with the bread 
from straight-grade flour, a fact which has been brought oul in refer- 
ring to the lower coefficients of digestibility of the breads from the 

coarser Hour-. In general, no differences in the gain- <>r losses of 

nitrogen were observed which could be attributed to the consumption 

of breads from different grade- of Hour. 



53 

GENERAL SUMMARY OF RESULTS AND CONCLUSIONS OF 
EXPERIMENTS WITH BREAD. 

In eighteen digestion experiments with men it was found that white 
(straight-grade) flour was more completely digested than either Gra- 
ham or entire-wheat floor, and yielded a larger amount of digestible 
nutrients and available energy. While Graham and entire-wheat 
flours contain more total protein and fat and have a higher heat of 
combustion, they actually yield to the body, because of their lower 
digestibility, smaller percentages of digestible nutrients and available 
energy than the straight-grade flour. 

The same general differences in digestibility of the three grades 
of flour have been noted in experiments with hard northwestern 
spring wheats grown in Minnesota and Dakota, hard winter wheat 
grown in Oklahoma, and soft winter wheats grown in Michigan, Indi- 
ana, and Oregon. In fifty -four digestion trials with both hard spring 
wheats and soft winter wheats in which six separate samples of wheat 
have been milled so as to produce the three types of flour — Graham, 
entire-wheat, and straight-grade — uniform results have been secured, 
and in all of the comparative trials the largest amounts of available 
nutrients and energy have been secured from the white flour. 

In the three digestion trials in which finely pulverized bran was added 
to white flour in the same proportion as is removed in milling, it was 
found that the addition of the bran lowered the digestibility of the 
flour so that a smaller amount of digestible nutrients and available 
energy was obtained from the bran flour than from the white flour with 
which the bran was mixed. The flour containing fineh T pulverized bran 
was more digestible than the coarsely granulated Graham flour, but 
less digestible than the white flour. When bran was finely pulverized 
it failed to digest as completely as the w T hite flour and, therefore, the 
addition of the bran lowered the food value of the flour. 

In three digestion trials in which finety pulverized wheat germ was 
added to white flour in the same proportion as is removed in milling, 
it was found that the addition of the germ did not materially change 
the digestibility of the flour, and that the amount of total digestible 
nutrients and available energy in the germ flour and the white flour 
was about the same. There was no material gain in total digestible 
nutrients by the addition of the germ to the white flour. The germ 
flour produced a smaller sized, sweeter, but less porous loaf than the 
white flour. Because of its fermentable character wheat germ is 
excluded from white flour. 

As to pecuniary value, a larger amount of available nutrients and 
energy can be procured at the usual prices for a given sum of money in 
the form of white, that is, straight-grade, flour than of any other flour. 
White flour contains the largest amount of available nutrients, and is 
not only the most digestible, but at present average market prices is 



54 

also the cheapest kind of flour. Ii Bhould not be inferred, however, 
that the use of entire-wheal and Graham flour is to in- discouraged. 
All the flours are very nutritious and economical foods, and experience 
has shown that they arc wholesome as well. Thr differences in the 
amounts of total nutrients furnished the body by the various grades 
of Hour are comparatively slight, all grades being quite thoroughly 
digested. 

In discussing the nutritive value of the breads made from the three 
kinds of flour, the quite noticeable effect of the breads upon the sub- 
jects is of interest. In the experiments reported all the subjects 
expressed a preference for the white bread. The Graham bread, when 
it furnished the hulk of the ration for four days, produced a little 
discomfort, suggesting a slight irritation of the digestive tract. The 
ration of white bread and milk was less bulky in character and gave 
better results as to satiety and particularly as to ease of digestion. It 
should be borne in mind, however, that the tendency <>f the coarser 
Hours to increase the peristaltic action of the intestines is often of 
undoubted value, particularly to persons of sedentary habit, and that 
their use as a laxative is in many cases extremely beneficial. 

The use of different grades of flour for bread making is a convenient 
means of increasing the variety of the diet. Because of varying 
requirements no general rule can be laid down in the matter, and the 
extent to which the various grades of flour should be used must be 
determined largely by the individual himself. 

In this investigation the comparative digestibility of the phosphates 
and other mineral constituents was not determined, nor were the quan- 
tities consumed and the amounts and proportions excreted in the urine 
and feces studied. As vet entirely satisfactory methods ha\ e net been 
generally adopted for determining the digestibility of mineral constit- 
uents, and consequently there is a lack of definite knowledge concern 
ing body requirements and the changes which are involved in the 
metabolism of the ash constituents of the diet. Considerable work 
along these lines is now being carried on by a number of investigators 
in France and elsewhere in Europe, and in tin 1 United States studies 
of the forms in which ash constituents, especially phosphorus, occur 
in food products, methods of estimating phosphorus, sulphur, and 
other ash constituents in food and excretory products, and various 
problems concerning the functions of these elements are being taken up 
in connection with the nutrition investigations of this Office and by 
expeiinient station workers and other investigators. It is believed 
that this work may be more appropriately summarized when the 

investigations now in progress have been continued for a longer time. 



THE DIGESTIBILITY AND NUTRITIVE VALUE OF MACARONI. 

INTRODUCTION. 

Macaroni and similar foods, grouped together under the name of 
Italian pastes, are commonly said to be of Italian origin, but as pointed 
out in a recent journal " there is reason for believing that the}^ were 
introduced into Sicily and Calabria by the early Greek settlers, and 
that the invention of these food products is to be ascribed to the 
Greeks. There are undoubtedly grounds for this statement, yet it 
should be remembered that similar food products have been known 
since earty times in China and Japan, where they are still manufac- 
tured in large quantities. 

Italian pastes are usually made from durum, or macaroni, wheat; that 
is, varieties which are of a glutinous character. The wheat is ground 
less finely than for ordinary flour-making purposes, the product being a 
coarse granular middlings known as semolina. In making macaroni 
this semolina is made into a stiff dough, kneaded and then pressed into 
tubes and dried. Though prepared for the table in a number of ways, 
the first treatment usually consists in parboiling the dried macaroni 
twenty to thirty minutes. 

In connection with investigations carried on by the Bureau of Plant 
Industry of this Department regarding durum wheat, information 
is given regarding the process of manufacture of macaroni and 
related topics in a recent bulletin, 6 and also in earlier publications 
the character of such wheat, the relative value of different varieties, 
and other questions are considered. At the South Dakota Experi- 
ment Station c the value of durum wheat flour for making bread, cake, 
and similar foods has been studied, and tests on the milling of this 
wheat and the manufacture of macaroni have also been made. 

The composition of macaroni and similar Italian pastes has often 
been determined by analysis, some of the work of this character hav- 
ing been carried on by experiment station investigators or those con- 
nected with the nutrition investigations of this Department. Rubner,^ 
Jacoangeli and Bonanni, 6 Cappelletti/ and perhaps other investigators 

"Home Sci. Mag., 20 (1903-4), p. 271. 
&U. S. Dept. Agr., Bureau of Plant Industry Bui. 70. 
c South Dakota Station Buls. 77 and 82. 
tfZtschr. Biol., 15 (1879), p. 115. 
«Bol. Not. Agr., 19 (1897), II, p. 434. 

/Ztschr. Untersuch. Nahr. u. Genussmtl., 1 (1898), p. 384. 
(55) 



have studied the composition of macaroni and similar goods, but the 
amount of available information on this subject is not large. 

In order t<> determine tin- nutritive value of macaroni made from 
American wheat, two series of experiments were undertaken which 
included the milling of the wheat, the preparation of the macaroni, 
and tlie determinations of its nutritive value when eaten by healthy 
young men who had a fair amount of muscular exercise. The wheat 
used in the series of experiments made in 1904 wan grown at the North 
Dakota Experiment Station, and that used in the experiments made in 
L905 was obtained at the North Dakota Substation, located at Edgeley. 
In both series the wheat was milled in the new experimental roller 
mill (PI. IX) at the Minnesota Experiment Station and the semolina 
manufactured into macaroni by the Minnesota Macaroni Company, of 
St. Paul. 

MILLING OF SAMPLES. 

In the milling system employed the cleaned wheat i- passed along to 
the first break, where it receives it- first reduction. The "chop" is 

carried to the sifter by mean- of an elevator and separated into break 
flour, middlings, coarse bran, and material for the second break, where 
similar streams are obtained. The middlings are reduced between 
smooth rollers, purified by the aspirator, bolted in the sifter, and the 
reduced and purified product recovered a- middlings Hour or patent 
flour. In the system of milling followed, two grades of middlings 
flour, i. e.. first and second, a break flour, and a Low-grade Hour, are 
obtained. From 7" to 7.". per cent of the wheat milled, depending 
upon its quality, is recovered as Hour with this experimental mill, and 
from 25 to 30 per cent is returned as bran, shorts, and feed. 

The genera] plan of the milling system is shown in the figure here- 
with (tig. 1). 

The milling plant used consists of two stands with corrugated and 
smooth rollers. By passing the material over the roll- a second 
time a four-break system of milling i- secured. The milling of durum 
wheat for the production of semolina requires a different granula- 
tion and bolting of the middlings from that used in the preparation 
of flour from ordinary hard wheat- for bread-making purposes. The 
aim i- to secure medium coarse granular middling-, i. »•.. semolina, 
rather than fine flour, and it follow- that the proportion of wheat 
obtained as middlings, which would ordinarily be reground, i- greater 
than in Hour milling. Manufacturer- state that for macaroni making 
Bemolina is required which will not pass through a No. L0 bolting 
'loth. In milling for bread-making purposes the flour must be fine 
enough to pass through a No. L0 or 1 1. and in some cases a No. 1l' or 
14 bolting cloth. 

For the investigations reported herewith the Kubanka varietj of 



U. S. Dept of Agr., Bui. 156, Office of Expt. Static 




57 



durum wheat was selected as this appears to be one of the best vari- 
eties both as regards yield and the quality of its milling- products. In 
each series of experiments the wheat selected was sound, bright, clean, 
and free from weed seeds, that used in 1904 weighing about 60 pounds 
to the bushel and that in 1905 about 63 pounds. As in ordinary 
milling, the wheat was softened or tempered by the addition of water 
prior to grinding. This prevents the bran from breaking up into fine 




f?FGRMD 



Fig. 1. — General plan of milling system. 



pieces and contaminating the flour. Owing to the hard, flinty nature 
of the durum wheat a longer time and more water is required for tem- 
pering than with ordinaiy wheat flour. About a quart of water per 
100 pounds of wheat was used, and the dampened grain was allowed to 
stand for twenty -four hours at a temperature of 20° C. before grinding. 
The samples were milled under the supervision of Mr. Robert 
Dewar, an experienced miller, who at the time was engaged in special 



58 

work in wheat and flour testing at the Minnesota School of Agricul- 
ture. The amount ground in L904 weighed 250 pounds, and that in 
the following year 172 pounds. It was noted that the electric current 
used for running the mill registered 28 to :'>•"> amperes instead of 25 to 
32 amperes, as in milling ordinary hard Kansas and Dakota wheats. 
The following table shows the kinds and amounts of milling products 
obtained from the two lots of wheat ground: 



Table 42.— Milling products obtain 


i dfrom durum wheat. 




Kiml of product 


Amount obtained. 


Experiments macU in v.«>:. 




Pound*. 










10 
15 

Jl 

7 

3 
































Elevator boots, flour and stock in 












250 










Espuhitntts math in V.M>.~. 


- 
16.6 








































172.0 









In the first milling- test 71.2 per cent of the wheat as milled wu 
recovered as flour: 26.1 percent as bran, shorts, and feed, and 1.2 per 
cent as aspirator dust. The total material recovered was a little less 
than the amount used, the loss in grinding being L.2 per cent. In the 
second test 62.1 per cent of the wheat used was recovered as middlings 
and flour of different grades, and 36.3 per cent as offals. The lo- 
in milling was 1.6 per cent. The higher flour yield in L904 was 
largely due to regrinding the tailings and offals. This resulted in 
lowering the commercial grade of the Hour, and hence was omitted 
in 1905. 

As noted above, in milling durum wheat the bran breaks readily 
and forms tine particle- which find their way into the shorts, and so 
it happens that the relative amounts of bran and shorts are about the 
opposite of those found in milling ordinary wheat. In milling ordi- 
nary varieties of hard wheat by this same milling system To t.. 7.". per 
cent of the grain is obtained as flour, including all grades. It w ill be 
-ecu. therefore, that there i> little difference in the total yield of floor 
from durum and ordinary varieties of hard wheat, when the offals 



59 

from the durum wheat are remitted. A comparison of similar data 
for the two sorts shows the relative proportion of different grades 
of Hour varies with the two types of wheat. Owing to the flinty 
character of the durum wheat there is a tendency for the stock to 
resist reduction and to tind its way into the tailings. This results 
in an unequal division of the work of reduction among the various 
stands of rollers. When the coarse middlings and tailings are reground 
the final milling products obtained are about the same as with ordinaiy 
wheat. 

COMPOSITION OF SAMPLES OF "WHEAT AND MILLING PRODUCTS. 

For purposes of comparison, samples of hard Scotch life spring 
wheat, grown under the same conditions as the durum wheat, were 
milled. 

The following table shows the composition of the durum wheats and 
the Scotch life wheats selected for comparison, and their milling prod- 
ucts, as well as of the macaroni made from the durum wheats: 



Table 43. — Composition of tin mm tint! hard spring wheats and llieir milling products. 



Kind of material. 



Pro- 


Fat. 


per ct. 


Per ct. 


12.37 


2.07 


11.69 


1.47 


10.78 


1.21 


11.75 


1.52 


12.36 


2.10 


11.64 


1.27 


14.05 


3.42 


12. 37 


3.22 


12.82 


4.21 


14.36 


5.48 


11.80 


1.27 


14.30 


2.05 


11.96 


1.11 


11.89 


1.28 


13.54 


1.42 


12. 45 


2.48 


11.11 


2.04 


11.95 


2.24 


12. 32 


1.67 


11.08 


2.19 


13.69 


2.14 


13.28 


5.39 


12.99 


7.93 


11.57 


89 


12. 09 


2.16 


10.60 


1.11 


11.39 


1.35 


11.00 


1.40 



Nitro- 
gen- 
fret- ex 
tract. 



Experiment* made in 190.',. 

Durum wheat 

Durum wheat millin.tr products: 

First middlings flour 

Second middlings flour 

Coarse middlings flour 

Break flour 

Mixed flour < Nos. 4S7, 4ss, 4S9, 490) 

Shorts 

Feed 

Bran, coarse 

Bran, fine 

Macaroni made from mixed flour No. 495... 

Hard Scotch life sprin.tr wheat 

Hard Scotch fife spring wheat milling prod- 
ucts: 

First middlings flour 

Second middlings flour 

Break flour 

Experiments made in 1905. 

Durum wheat 

Durum wheat milling products: 

First middlings flour 

Second middlings flour 

Coarse middlings flour 

Break flour 

- Tailings flour 

Bran 

Shorts and feed 

Macaroni made from mixture of flours Nos. 

601,602,603,604 

Hard Scotch rife spring wheat 

Hard Scotch fife spring wheat milling prod- 
First middlings flour 

Second middlings flour 

Break flour 



10..S5 
10. N2 
10.72 
11.32 



11.95 
10.84 
11.51 



10.84 
9.91 
10.36 
12. 09 
10.43 
11.77 
11.10 



75.20 
76.52 
75. 29 



74.56 
75.54 
73.00 



2.32 
1.94 
5.25 
5.06 



60 

A- will be seen, the durum wheat used in 1904 contained L2.37 per 
cent of protein, while the hard Scotch fife wheat grown upon an 
adjoining field contained L4.30 percent; the durum wheat used in L905 
contained li\4.*> percent and the hard Scotch fife wheat 12.09 percent 

As is often the case, there i- some difference in the appearance of 
the individual kernels of the durum wheat, and in connection with 
some work carried on at the Minnesota Experiment Station' the 
amount of protein in kernel- of various character was studied. An 
average -ample of the durum wheat milled in L904 contained L2.87 per 
cent protein. Selected, dark-colored, hard, glutinous kernels showed 
12.76 per cent, and light-colored, soft, starchy kernels, L0.60 percent. 
Medium perfect kernels contained L2.56 per cent and small but equally 
well-filled one- 11.19 per cent. In former investigations* it ha- been 
shown that as a general rule the proportion of protein in standard pat- 
ent flour i- only ".6 to 0.7 per cent less than in the wheat from which 
it was milled. In the case of the durum wheat the mixed floor or 
semolina contained 0.7:; per cent less protein than the whea or 
approximately the same proportion a- in the case of average bard 
wheat. As shown by the analyses reported, the durum wheat floor 
ground in 19<>-± and the flour and other milling product- made from it 
contained about the same percentage amount- of protein, fat. and 
carbohydrates as are found in an average bread wheat and it- milling 
product-. 

In durum wheat flour No. 4!*."* it was found that 43.9 per cent of tin- 
total nitrogen present was in the form of gliadin. In patent floors 
made from hard spring wheat the gliadin nitrogen constitute- 52 to 61 
per cent of the total nitrogen.' In the milling test carried on in 1906 
it was observed that the durum wheat and also the ordinary wheat 
grown in the same locality contained less protein than the wheat - 
ground the preceding year, and in fact a -mailer proportion of this 
constituent than is usually the case with the local hard wheat-. This is 
due. it is believed, to unusual climatic condition-, i. •-.. excessive rain- 
fall and low temperature which prevailed during the growing season 
of the wheat.-. Notwithstanding it- low protein content, the durum 
wheat selected i- believed to be typical of similar wheat- grown the 
same season in that part of Dakota. The Hour samples milled from 
the durum wheat -how in general the same percentage composition a- 
those milled from the ordinary hard spring wheat selected for pur- 
po-e- of comparison. 

a Minnesota station BuL 85, \>. L86. 

1 -. Dept Agr., Office of experiment Stations Bnl. 101, p. in. 
e Minnesota Station BuL 85, p. 207. 



61 



MANUFACTURE OF THE MACARONI. 

In both tests the semolina used for the manufacture of macaroni 
included all the Hour and middlings except the dark-colored break 
flour. The mixture was somewhat more linel} r ground and a little 
darker in color than that used for the commercial grades of macaroni, 
but it was the object to use as much of the wheat kernel as possible 
without including the break flour and offals rather than to prepare a 
high-grade commercial article which would include only a part of the 
middlings. 

The macaroni was made in the presence of the author, the process 
of manufacture being as follows: The semolina was first mixed with 
about 30 per cent of water and made into a stiff dough by means of a 
mixing machine such as is used for bread-making purposes in many 
bakeries. The dough was then kneaded in a second machine provided 
with heavy iron rollers and passed to a third machine, where it was 
rolled into long thin sheets and Anally made into rolls a foot or so in 
diameter and about 3 feet long. These rolls were placed in cylindrical 
presses provided with a perforated plate in the bottom with a wire sus- 
pended in each opening, though not so as to completely close the per- 
foration. The dough is pressed through these orifices, making long, 
hollow tubes about one-eighth inch in diameter. The macaroni as it 
comes from the machine is spread by hand on trays, is cut into the 
desired lengths, and placed in racks to dry in the curing room at a tem- 
perature of 70° F. From seven to ten days are required for the 
drying and curing of the macaroni and it is then packed and ready 
for use. 

The water used in mixing the dough is practically all removed in 
drying the macaroni, and, in this investigation, the analysis of the dry 
macaroni showed that it contained about the same percentage of mois- 
ture as the original flour or semolina. The conditions under which 
the drying takes place would suggest that but little loss of dry matter 
due to fermentation is possible. Indeed, mechanical losses appear 
to be the main losses in the preparation of macaroni, and these are not 
large. The conditions under which this macaroni was made did not 
permit of careful weighing of the flour and the finished product with 
a view to studjdng the losses and changes during manufacture. In 
fact, a study of its nutritive value was the object sought rather than 
a technical chemical study of the preparation of macaroni. 

In the first test the composition of the mixed flour used for macaroni 
making was recorded. As will be seen by referring to Table 43, this 
flour (No. 495) and the uncooked macaroni made from it (No. 495A) 
have practically the same composition. A microscopic examination 
of the macaroni suggested that there was a slight change in the form 



62 

and character of the starch granules due to the treatment received 
during the process of manufacture. The action of the water, the 
kneading, roiling, and drying influenced tin- physical character of the 

macaroni and possibly caused a slight hydration of the starch and 
proteids without materially affecting their percentage amounts. 

COMPOSITION OF SAMPLES OF FOOD MATERIALS. 

In connection with the digestion experiments -ample- of the food 
materials were analyzed in the usual way (see page L3). In the case 
of macaroni, samples of the raw material were analyzed. Composite 
samples of the bread were prepared for analysis in the way described 
on page 15. For each experimental period a composite -ample of the 
milk or cream, which formed a part of the ration, was prepared by 
placing in a can each day quantities proportional to the total amount- 
consumed, potassium bichromate being used a- a preservative. The 
following table shows the composition of the food- used in the diges- 
tion experiments: 

Table 44. — Cowjioxitinn of foo<l materials used m digestion experiments with macaroni 

and durum whoit hnakfasi foot/. 



Kind of material. 



< ■urli..- 




hy- 


Ash. 


drates. 




/■- r n. 






0.71 




.93 




1.02 


1.90 


.78 


4.65 


.75 


79. 06 


"I 


! - 




i 92 









Beat at 
combus- 
tion per 

gram. 



E.rpi rimi nts madt ft 



Milk, composite sample. 



Experiments mad* ft 



Macaroni, raw 

Durum wheal breakfast fond . 

Milk 

Cream 



Pt r rl. 
12.01 
36.50 



1 1 . 57 . 89 

ll.li 2.12 

2.98 1.12 

8.37 10.65 



2 W 



COMPOSITION OF FECES AND URINE. 

The urine and feces were collected for analysis in the usual way. the 
separation of the feces pertaining to each experimental period being 
secured by the use of lampblack taken in capsules." A composite -am- 
ple of urine was prepared for analyses by uniting aliquot samples of 
the quantities voided each day. A small amount of formalin wa- u-ed 
to prevent fermentation, and the samples were kept in a cool place. 
Tables 45 and 4(5 show the composition of the dry matter of the feces 
and the amount, specific gravity, and nitrogen content of the urine in 
the digestion experiments. 

«U. S. Dept. Alt.. Office of Experiment Stations Bui. L43. 



63 



'able 4o. — Composition 



& 



tfdn/ matter of/ecex from digestion experiments with 



macaroni. 



Whence obtained. 



Experiment No. 493.. 
Experiment No. 494.. 
Experiment No. 495. . 
Experiment No. 490.. 
Experiment No. 497. . 
i Experiment No. 498.. 
Experiment No. 592. . 
Experiment No. 593.. 
Experiment No. 594.. 
Experiment No. 595. . 
Experiment No. 596. . 
Experiment No. 597. . 



Per cent. 
29. 52 
24. 10 
27. 22 
28. 07 
23.94 
32.59 
29.76 
23. 75 
28. 97 
20. 15 
16.92 
21.91 



10. 42 
12. 24 
10. 06 
10.07 



13.47 
8.01 
8.52 

11.06 



39.07 I 
29.91 
30.34 
39.07 



30. 00 
26. 93 
27.43 
30.44 

28.56 
24. 53 
20. 75 
15.66 



Heat of 
combus- 
tion per 



4.879 
5.302 
4. 269 
4.197 
5.106 
4. 240 
4.159 
4.776 



Table 46. — Amount, specific graritg, and nitrogen of urine from digestion experiments with 
macaroni. 



Whence obtained. 



Total 


Specific 


voided . 


gravity. 


Grains. 




5,506 


1.027 


4,546 


1.033 


5,230 


1.025 


6,545 


1.027 


6,655 


1.031 


6,655 


1.027 


1,619 


1.024 


3,826 


1.032 


4,722 


1.029 


3,828 


1.025 


4,021 


1.030 


5,482 


1.022 



Experiment No. 493 
Experiment No. 494 
Experiment No. 495 
Experiment No. 496 
Experiment No. 497 
Experiment No. 498 
Experiment No. 592 
Experiment No. 593 
Experiment No. 594 
Experiment No. 595 
Experiment No. 596 
Experiment No. 597 



1.28 
1.62 
1.13 
1.06 
1.20 
1.04 
1.04 



EXPERIMENTAL METHODS. 

The general plan of these digestion experiments was the same as 
that for the comparison of the entire-wheat, graham, and straight- 
grade breads, described on page 18. All of the food consumed for 
a period of four days was weighed, sampled, and analyzed, as well as 
all the urine and feces pertaining to the experimental period. 

In the calculation of the digestibility of the macaroni and durum 
wheat flour bread together, in the experiments made in 1904, and of the 
macaroni in those made in 1905, the milk which formed part of the 
ration was assumed to have the following digestibility: Protein, 97 per 
cent; fat, 95 per cent; carbohydrates, 98 per cent; energy available to 
the body, 95 per cent. These are the figures used in the digestion 
experiments with bread and milk already described in this bulletin. 

The digestibility of the cereal alone in the experiments made with 
the breakfast food prepared from durum wheat was computed on the 
assumption that 97 per cent of the protein and 95 per cent of the fat 
of the cream eaten with it were digested. 



64 

DETAILS OF THE DIGESTION EXPERIMENTS. 

In tlif first series of tests >i.\ experiments were made to determine 
tlif digestibility and nutritive value of the specially prepared macaroni. 
In order to give variety to the diet without using any considerable 
number of food materials, bread made from some of the flour used for 
the manufacture of the macaroni formed a part of the ration. This 
flour made bread of good quality, with a characteristic yellow tinge. 
The loaf was not quite as large or of bo good quality as thai made from 
a like amount of the bard wheal patent flours made from samples 
No-. 4!»7 and 498. The only food used in addition to cooked macaroni 
and bread made from durum wheat flour was milk. In the first three 
experiments about one-third more macaroni than bread (on the di\ 
matter basis) was used, while in the last three experiments the ration 
contained about two and a half times as much macaroni as bread. The 
subjects were healthy men engaged in moderately severe labor. In 
each case three subjects were used, and each experiment covered a 
period of four days. 

The macaroni was prepared for the table by cooking in boiling 
water for twenty minutes, and a weighed quantity of the dried mate 
rial was cooked separately for each subject. The water was drained 
off and a small amount of milk added. The macaroni was then warmed 
in an oven and served. Analyses were made of the waters drained 
from the cooked macaroni and it was found that they contained from 
0.03 to 0.04 per cent of the total nitrogen originally present in tin- 
macaroni, as well as a somewhat larger amount of carbohydrates. In 
ordinary household practice the material removed would be lost, a- 
the water in which the macaroni was cooked would be thrown away. 
The material lost constitutes about 2.25 per cent of the soluble mate- 
rial originally present in the macaroni, which is about the same quan- 
tity as is lost by the processes of fermentation followed in bread 
making/' It is natural to suppose that the quantity of water used 
would affect the amount of material dissolved from the macaroni, and 
it is obvious, therefore, that when 1 strict economy i- desired small 
rather than large amounts of water should be used. In calculating 
the results of the digestion experiments made in L904 a correction was 
• introduced for the proteids lost in cooking by deducting 0.03 per cut 
of nitrogen from the total amount present in the original material. 
With this correction it was found that the dry matter of the uncooked 
and the cooked macaroni had practically the -nine percentage compo- 
sition. When compared on the basis of dry matter, little, if any. 
difference was observed between the com posit ion of the durum flour, 
the cooked macaroni, and the durum-flour bread. In the experiments 
made in L905, the quantities of nutrient- supplied by the cooked 

"l\ s. Dept Agr., Office oi Experiment Stations BuL 87, 



65 



macaroni were computed on the basis of the composition of the raw 
material, as the work of the previous } r ear had shown that the com- 
position of the air-dried, cooked, and raw macaroni was so similar 
that no appreciable error was introduced by this method. 

In the second series, three digestion experiments were made with a 
ration limited to macaroni and milk. The subjects, healthy young 
men engaged in moderate muscular work, were not inconvenienced by 
the simple character of the diet and it is believed that the results 
obtained may be regarded as normal. 

For purposes of comparison three digestion experiments were also 
made with a breakfast cereal made from durum wheat. During the 
processes of manufacture of this rolled- wheat preparation a part of 
the bran was removed. This breakfast food, cooked in water in the 
usual way, was palatable and in flavor very much like similar break- 
fast foods prepared from ordinary wheat. It was eaten with cream, . 
these two articles constituting the entire ration. 

The details of the separate digestion experiments and the income 
and outgo of nitrogen are given in Tables 47 to 52. 

EXPERIMENTS WITH MACARONI AND DURUM WHEAT BREAD. 

DIGESTION EXPERIMENT NO. 493. 

Kind of food. — Milk, macaroni, and bread made from durum flour. 
Subject. — Man No. 1, 21 } T ears of age, ernploj T ed at farm labor. 
Weight. — At the beginning of the experiment 173.5 pounds; at the 
close 173.25 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
June 11, 1901. 

Table 47. — Result* of digestion experiment Xo. 493. 



Sam- 
ple 
No. 




Weight of 

material. 


Protein 
(NX6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


Grams. 
900.0 
965.0 

7, 050. 


Grams. 
104.8 
78.9 
229.1 


Grams. 

11.4 

8.6 

343.4 


Grains. 
669.3 
515.9 
345.5 


Grams. 
6.4 
9.3 
55.0 


Valor its. 






2,715 




Milk 










Total 




412.8 


363.4 


1,530.7 


70.7 


12,012 






86.0 


25.4 
6.9 


14.2 
17.2 


25.7 
6.9 


20.7 












Estimated feces from mac- 












18.5 




18.8 






















387.4 
165.2 


349.2 


1,505.0 
1,166.4 


50.0 






Estimated digestible nutrients 








Coefficients of digestibility of 














Per cent. 


Per cent. 
96.1 


Per cent. 
98.3 
98.4 


Per cent. 

70.7 


Per cent. 
(96.5) 
(97.2) 




Estimated coefficients of digest- 






Proportion of energy actually 
available to the body: 
























1 













29604— No. 156—05- 



During this experiment the subject eliminated 5,506 grams urine, 
containing* 70,48 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food L6.51 grams; outgo in 
urine 17.62 grains; and in feces 1.02 gram-: implying a loss of 2.18 
grams nitrogen, corresponding to 13.3 grams protein. 

DIGESTION EXPERIMENT NO. 494. 

Kind of ' f>< od. — Milk, macaroni, and bread made from durum flour. 

Subject. — Man No. 2, 21 years of age. employed at farm labor. 

Weight. — At the beginning of the experiment 178.5 pound-: at the 
close 179 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
June 11, 1904. 

Table i8.— Results of digestion experiment No. •/'•''-/'. 



pie 

No. 




Weight of 

material. 


Protein 


Fat. 


Carbohy- 
drate-. 


Asb. 


Energy. 


501 
500 
502 


Food consumed: 

Macaroni 

Bread 

Milk 

Total 


1,300.0 
1,280.0 
8,615.0 


Orams. 
151.8 

104.7 
280. 


Grams. 
16. 5 

11.4 
419.6 


422. 1 


12.4 


8,601 
7,116 






536.0 


447. 5 


2.073.2 


88.9 


15, 735 




144.0 


34.7 

s. 1 


21.4 
21.0 


53.8 
8.4 


34.1 






Estimated feces from milk 

Estimated feces from mac- 














26.3 




4.".. 4 








Total amount digested . .. 
Estimated digestible nutrients 














501.3 

229.7 


426. 1 


2, 019. 4 
1,605.7 


54.8 


14.971 




Coefficients of digestibility of 












Percent 

93.5 
- J 


95. 2 


/'' r Ct Hi- 
97.4 
97.3 


l't r a iti. 
61.7 


91.2 




Estimated coefficients i >f digesti- 
bility of macaroni and bread . 

Proportion of energy actually 
available to the body: 










































During this experiment the subject eliminated 4..~.4<i grams urine, 
containing 73. li.") grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 21.44 grams; outgo in 
urine 18.41 grams; and in feces 1.39 grams; implying a gain of 1.64 
grams nitrogen, corresponding to 10.3 gram- protein. 

DIGESTION EXPERIMENT NO. 495. 

Kind of food. — Milk, macaroni, and bread made from durum flour. 

Subject. — Man No. 3. 25 years of age. employed at janitor work. 
Weight. — At the beginning of the experiment 140.5 pounds; :it the 
close 140.5 pounds. 

Duration. - Four days, with twelve meals, beginning with breakfast 
June 11, 1904. 



67 

Table 49. — Retail* of iliijestion experiment Xo. 495. 



Sam- 
ple 
No. 


Weight of 
material. 


Protein 
(N <6.25) 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


1,250.0 
1,283.0 
6, 325. 


Grams. 
145. 5 
104.9 
205. 6 


lira nis. 
15.9 
11.4 
308.0 


Grams. 
929. 6 
685. 9 

309.9 


Grams. 
8.9 
12.5 
49.3 


Calories. 






3,609 










Total 








456.0 


335. 3 


1,9-25.4 


70.7 


13,658 


505 


149. 


40.6 


15.5 
15.4 


61.8 
6.2 


31.1 












Estimated feres from mac- 












34.4 




55.6 






















415. 4 

216. o 


319.8 


1,863.6 

1,559.9 


39.6 






Estimated digestible nutrients 








Coefficients of digestibility of 














Percent. 

91.1 
86.3 


Per cent. 
95.4 


Per cent. 
96.8 
96.6 


Per cent. 
56.0 


Per cent. 
(95.3) 
(94.9) 

91.5 




Estimated coefficients of digesti- 






Proportion of energy actually 
available to the body: 




















91.7 


















During this experiment the subject eliminated 5,230 grams urine, 
containing 59.10 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food IS. 24 grams; outgo in 
urine 14.78 grams; and in feces 1.62 grams; implying a gain of 1.81 
grams nitrogen, corresponding to 11.5 grams protein. 

DIGESTION EXPERIMENT NO. 496. 

Kind of food. — Milk, macaroni, and bread made from durum flour. 

Subject. — Man No. 1. Conditions as in experiment No. 193. 

Weight. — At the beginning of the experiment 173.25 pounds; at the 
close 171 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
June 15, 1901. 

Table 50. — Results of digestion experiment Xo. 496. 



Weight of Protein 
material. (N ■ 6.25). 

Food consumed: : Grams. Grams. 

Macaroni 1,275.0 I 148.4 

Bread ' 630.0 i 54.6 j 

Milk " 

Total 

I Feces (water-free) 

, Estimated leces from milk 

; Estimated feces from mac- 
aroni and bread 

Total amount digested .... 

Estimated digestible nutrients 

in macaroni and bread 



Ash. Energy. 



8,875.0 I 


305.3 


415.4 


412. 7 


66.6 


7,402 




508.3 | 


437.5 


1,717.9 


82.0 








123.0 j 


« 


15.1 
20.8 '■ 


36.5 ; 


36.9 ! 


516 










j 


25.3 !. 




28.2 L 














473.8 , 
177.7 j. 


422. 4 


1,681.4 

1,277.0 . 


45.1 


13, 686 









68 



Table 60. — Results of digestion experiment No. 466 — Continued, 



8am- 




Weight of 
material. 


Protein ,., , 

hat. 


Carbohy- 
drates, 


A-b. 




Coefficients of digestibility of 




98. 2 

- 






rMimated coefficient* '""'' - 




Proportion of energy actually 
available to tin- body: 



























During this experiment the subject eliminated 6,545 grams urine, 
containing 69.38 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 20.33 grams; outgo in 
urine 17.35 grams; and in feces 1.38 grams; implying a gain of L.60 
grams nitrogen, corresponding to 1 ( » grams protein. 

DIGESTION EXPERIMENT NO. 497. 

Kind of fond. — Milk, macaroni, and bread made from durum 

flour. 

Subject. — Man Xo. •!. Conditions as in experiment No. 494. 

Weight. — At the beginning of the experiment 17'.' pounds; at tli« i 
close 177.5 pounds. 

Duration. — Four days, with twelve meals, beginning with break- 
fast June 15, 1904. 

Table 51. — Retails <>f <l I <!,. **;,,,, , rperimenl No 4S7- 



Sam- 
ple. 
No. 




Weight of 

material. 


Protein 


Fat. 


Carbohy- 


Lab. 


Energy. 




Food consumed: 


Grams. 

1,575.0 

816.0 

9,275.0 


Grams. 

70.7 
319.1 


7.7 
434.1 


(inim*. 

1.171.4 

162. 1 


11.2 










509 


Milk 






Total 









573. 1 


461.8 


2,065.1 


89.0 


16. 24* 






132.0 


\< 


13.3 

21.7 


51.6 


35.5 












Estimated feces from maca- 












22.0 




43.0 




















541.5 
232.0 


44*. 5 


2,013.5 
1,590.8 


53.5 


15,574 




Kstimated digestible nutrients 








Coefficients of digestibility oi 














I'.r cent 
94.5 
91.8 


/'' r c> lit. 

97. 1 




Per cent. 


Per c at 




Estimated coefficients of diges- 
tibility of macaroni and bread. 

Proportion of energy actually 
available to the l«nly: 














































During this experiment the subject eliminated 6,655 grams urine. 
containing 79. 86 grams nitrogen. The average nitrogen balance per day 



69 

was therefore as follows: Income in food 22.93 grams; outgo in urine 
19.97 grams; and in feces 1.26 grams; implying a gain of 1.70 grams 
nitrogen, corresponding to 10.6 grams protein. 

DIGESTION EXPERIMENT NO. 498. 

Kind of food. — Milk, macaroni, and bread made from durum flour. 

Subject. — Man No. 3. Conditions as in experiment No. •195. 

Weight. — At the beginning of the experiment 110.5 pounds; at the 
close 138.5 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
June 15, 1904. 

Table 52. — Results of digestion experiment No. 498. 



Sam- 


Weight of 

material. 


Protein 
(NX6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 




Food consumed: 


Grams. 

1, 305. 

657.0 

6, 225. 


Grams. 
151.9 
57.0 
214.1 


Grams. 

16.6 

6.2 

291.3 


Grams. 
970.5 
372.3 

2S9.5 


Grams. 
9.3 

6.7 
46.7 


Calories. 
























423. 


314.1 


1,632.3 


62.7 














124.0 


40.4 
6.4 


12.5 
14.6 


37.1 
5.8 


34.0 












Estimated feces from mac- 












34.0 




31.3 




















382.6 
174.9 


301.6 


1,595.2 
1,311.5 


28.7 


11 66'' 




Estimated digestible nutrients 








Coefficients of digestibility of 












Per cent. 
90.5 

83.7 


Per cent. 
96.0 


Per cent. 
97.7 
97.7 


Per cent. 

45.7 


Per cent. 

(95.7) 
(95.4) 




Estimated coefficients of digesti- 






Proportion of energy actually 
available to the body: 






















92.3 



















During this experiment the subject eliminated 6,655 grams urine, 
containing 69.21 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 16.92 grams; outgo in 
urine 17.30 grams; and in feces 1.62 grams; implying a loss of 2 
grams nitrogen, corresponding to 12.5 grams protein. 

EXPERIMENTS WITH MACARONI. 
DIGESTION EXPERIMENT NO. 592. 

Kind of food. — Macaroni and milk. 

Subject. — Man No. 1. College student 27 years old, engaged part of 
the time at light work. 

Weight. — At the beginning of the experiment 150 pounds; at the 
close 150^ pounds. 

Duration. — Four da} T s, with twelve meals, beginning with breakfast 
February 21, 1905. 



70 



Tablb 53.— Re»ult» of digestion ■ cperimeni \ 



Sam- 
pie 

NO. 


Weight of 
material. 


Protein 


Fat. 


Carbohy- 
drates. 


Ask 




593 
582 


Food consumed: 

Milk 

Macaroni 

Total 


1,070 

1 . 226 


121.29 


Grams. 
167.68 
10.90 




11. Lfi 






6,296 


263.02 




1,16k. 73 


43.71 


8.229.9 




98 


29.16 


9.27 


29. 73 
LOO 


29.83 












Estimate] feces from maca- 
roni 
















26.71 


















233. 86 
116.21 


169.31 


1.139.00 
942. 76 


13.88 






Estimated digestible nutrients 









Coefficients of digestibility <>i 














l'i r a nt. 
81.99 


94.81 


97.34 


Per cent. 


l-(r r, 7i/. 
(96.06) 




Estimated coefficients of digesti- 








Propoftion of energy available 
to body: 





































During this experiment the subject eliminated L, 619 grams urine, 
containing 16.84 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food L0.58 grains^ outgo in 
urine 4.21 grams; and in feces 1.17 grams; implying :i gain of 5.90 
grams nitrogen, corresponding to 32.5<> grams protein. 

DIGESTION EXPERIMENT NO. 593. 

Stnd of food. — Macaroni and milk. 

Sityect.—M&n No. i ; . Student 22 years old, engaged three hours 
per day at manual labor. 

Weight. — At the beginning of the experiment 183 pounds; at the 
close 182 pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
February 21, 1905. 

Table 54. — Result* of digestion experiment A 



Sam- 




Weight of 

material. 


Protein 


Fat. 


Carbohy- 
drates. 




Energy. 




Food '.insumed: 

Milk 


5.050 
1,500 


178.66 


13.35 




to. 10 




582 








Total 






6,550 


324. 04 


2-21.41 


1. 184.86 


51.05 


10. 12V 6 


598 


100 


23. 75 
4.51 


8.62 


9.07 


28.56 












Estimated feces from mac- 












19.24 




34.10 






















300.29 
154.31 


212. 79 


1,395.29 
1,151.80 








KM i ma tod digestible n m ri<-nt~ 










=— 







71 

Table 54. — Results <>f digestion experiment Xo. 593 — Continued. 



*»g- Weight of 
g." material. 


Protein 
(NX6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 


Coefficients of digestibility of 


Per cent. 


Per cent. 


Per cent. 
97. 28 

97. 12 


Per cent. 


Per cent. 
(95. 28) 

(95.21) 


Estimated eoeffieientsof digesti- 
bility of macaroni 


88.91 






Proportion of energy available 
to body: 












91.73 




1 " 


! 



During this experiment the subject eliminated 3,S26 grams urine, 
containing 45.91 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 12.96 grams; outgo in 
urine 11.48 grams; and in feces 0.95 gram; implying a daily gain of 
0.53 gram nitrogen, corresponding to 3.31 grams protein. 

DIGESTION EXPERIMENT NO. 594. 

Kind of food. — Macaroni and milk. 

Subject. — Man No. 3. College student 23 years old, with exercise 
equivalent to two hours per day of light work. 

Weight. — At the beginning of the experiment 182 pounds; at the 
close ISO pounds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
February 21, 1905. 

Table 55. — Results of digestion experiment Xo. 594. 



Sam- 
ple 
Xo. 




Weight of 


Protein 
(NX6.25). 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 


593 
582 


Food consumed: 

Milk 

Macaroni 

Total 


•1,850 
1,375 


Grams. 
144. 53 
159. 09 


Grams. 
199. 82 
12. 24 


Grams. 

238. 62 

1,087.08 


Grams. 
38.80 
12.51 


Calories. 
3,734.5 
5, 720. 




6,225 


303. 62 


212. 06 


1,325.70 


51.31 


9,454.5 


599 


114 


33. 02 
4.34 


15. 35 

9.99 


37. 65 

4.77 


27. 96 












Estimated feces from mac- 












28.68 


5.36 


32.88 




















270. 60 
130.41 


196. 71 

6.88 


1,288.05 
1, 054. 20 


23.35 






Estimated digestible nutrients | 






Coefficients of digestibility of 












Per cent. 

89.12 
81.97 


Per cent. 

92.76 
56.21 


Per cent. 

97.16 
96.97 


Per cent. 


Per cent. 
(93.98) 
(92.82) 




Estimated coefficients of digesti- 








Proportion of energy available 
to body: 


















89.34 

















During this experiment the subject eliminated 4,722 grams urine, 
containing 59.03 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 12.15 grams; outgo in 
urine 11.76 grams; and in feces 1.32 grams; implying a daily loss of 
3.93 grams nitrogen, corresponding to 21.56 grams protein. 



EXPERIMENTS WITH DURUM WHEAT BREAKFAST FOOD. 
DIGESTION EXPERIMENT NO. 595. 

Kindoffood. — Durum wheat breakfast food and cream. 

Subject.— Man No. 1. College student 27 years old, engaged pari of 
the time at light work. 

Weight. — At the beginning of the experiment 153 pound-: at the 
close 152 pounds. 

Duration. — Four days, with twelve meal:-, beginning with breakfast 
February 17, 1905. 



-Results of digatio 



■ 1 1„ rirru nt No. 686. 



Sam- 
ple 

No. 




Weight of Protien 

material. I N 6.25). 


Fat 


Carbohy- 
drates. 


A-b. 






Food consumed: 


Oranu. Oratru. 
1,720 57.96 
1,075 119.76 


Oranu. 


Grama 


Oranu. 

n. in 
16.56 




587 


Durum wheat breakfast fund 


22. 79 








205.97 , 892.27 


30.66 
















182 


36. 67 
1.74 


14.5* • y.-.ys 
9. 16 1 1 . 97 


37.77 












Estimated feces from du- 
rum wheat breakfast fond 












34. 93 


5.42 ; 91.01 


















141.05 










Estimated digestible nutrients 
from durum wheat breakfast 




























Coefficients of digestibility of 




79. 37 
70.83 


Per <•- ni. 
92.9-2 

7) :: 


Per cent. 
88.54 


Per cent. 


Per cent. 

(87.96) 




Estimated coefficients of digesti- 
bility of durum wheat break- 








Proportion of energy available 
to body: 








In durum wheat breakfast 























During this experiment the subject eliminated 3,828 gram- urine, 
containing 32.92 grams nitrogen. The average nitrogen balance per 
day was therefore as follow-: Income in food 7.11 grams; outgo in 
urine 8.23 grams; and in feces 1.47 grams-: implying a daily loss of 
2.59 grams nitrogen, corresponding to 16.19 grams protein. 

DIGESTION EXPERIMENT NO. 596. 

Kind of food. — Durum wheat breakfast food and cream. 

Subject. — Man No. 2. Student 22 year- old, engaged three hours 
per day at manual labor. 

Weight. — At the beginning of the experiment L82 pound-; at the 
close 181 pound-. 

Duration. — Four day-, with twelve meals, beginning with breakfast 
February 14, L905. 



73 



Table 57. — Results of digestion experiment Xo. 596. 



Sam- 
ple 
No. 


Weight ot 
material 


Protein 
(N 6.25). 


Fat. 


Carbohy- 


Ash. 


Energy. 


583 
687 


Food consumed: 


Grams. 

2,240 
1,400 


' 75.49 
155. 96 


Grams. 
238. 56 

29.68 


Grams. 


Grams. 
18.37 

21.56 


Calories. 


Durum wheat breakfast food. 


5, 628. 


3. 640 


231.45 


268. 24 


1,102.03 


39.93 


9,391.2 






1:26 


19.94 
11.93 


137. 83 


36.64 






Estimated feces from cream 

Estimated feces from du- 
rum wheat breakfast food 




157.4 






37.33 


8. 01 


135. 27 




1 00" 3 














191. 86 
118.63 


248.30 
21. 67 


1,024.20 
898. 63 




a Jos 5 




Estimated digestible nutrients 






4, 622. 7 












Coefficients of digestibility of 








Per cent. 
82. 89 

76.06 


Per cent. 
92.56 

73. 01 


Per cent. 

S8.14 

86. 92 


Per cent. 


Per cent. 

(87. 62) 

(S2.14) 




Estimated coefficients of digesti- 
bility of durum wheat break- 








Proportion of energy available 
to body: 








In durum wheat breakfast 


















i 







During- this experiment the subject eliminated 4,021 grams urine, 
containing 47. So grams nitrogen. The average nitrogen balance per 
da}' was therefore as follows: Income in food 9.26 grams; outgo in 
urine 11.96 grams; and in feces 1.58 grams; implying a daily loss of 
4.28 grams nitrogen, corresponding to 26.75 grams protein. 

DIGESTION EXPERIMENT NO. 597. 

Kind of food. — Durum wheat breakfast food and cream. 

Suhject. — Man No. 3. College student 23 years old, with exercise 
equivalent to two hours per day of light work. 

Weight. — At the beginning of the experiment 181 pounds; at close 
182 rxmnds. 

Duration. — Four days, with twelve meals, beginning with breakfast 
February 14, 1905. 

Table 58. — Results of digestion experiment Xo. 597. 



Sam- 
ple 




Weight of 
material. 


Protein 


Fat. 


Carbohy- 
drates. 


Ash. 


Energy. 


583 
587 


Food consumed: 

Cream 

Durum wheat breakfast food . 

Total 


Grams. 

2,720 

1,700 


Grams. 
91.66 
189.38 j 


36.04 


" 155. 58 
1, 255. 45 


Gravis. 
22.30 

26.18 


Calories. 
4, 569. 6 
6,834.0 




4.420 


281.04 


325. 72 


1,411.03 


48.48 


11, 403. 6 




253 ; 


55.43 


27. 98 
14.48 


129.38 
3.11 


40.20 






Estimated feces from cream 

Estimated feces from du- 
rum wheat breakfast food 

Total amount digested 

Estimated digestible nutrients 
from durum wheat breakfast 














52.68 


13.50 


126.27 
















225.61 
136.70 


297. 74 
22. 54 


1,281.65 
1.129.18 
























74 



Table 58.— Results of digestion experiment No. 597 — Continued. 



Sam- 
ple 
&o. 


Weight oi Protein 

material 


Fat. 


Ash. Energy. 




Coefficients of digestibility of 




80.28 


»]. 11 

62.64 


Percent. Percent. 








Estimated coefficient- of digesti- 
bility of durum wheat break- 






Proportion of energy available 
to body: 








In durum wheat breakfast 
















During this experiment the subject eliminated 5,482 grams urine, 
containing 43.31 grams nitrogen. The average nitrogen balance per 
day was therefore as follows: Income in food 11.24 grams; outgo in 

urine 10.83 grams; and in feces 2.22 grains; implying ;i daily 1<>^ of 
1.81 grams nitrogen, corresponding to 11.31 grams protein. 

SUMMARY OF DIGESTION EXPERIMENTS WITH MACARONI AND 
DURUM WHEAT BREAKFAST FOOD. 

The table below summarizes the results of the digest ion experiments 
which were made with a ration of macaroni with durum wheat flour 
bread and milk, macaroni with milk, and durum wheat breakfast food 
with cream. For purposes of comparison the average results obtained 

in 21 experiments previously reported." with a diet of patent wheat 
flour bread and milk, are also included. 

Table 59. — Digestibility of nutrients <u«\ availability of energy of entire rations containing 
macaroni una durum wheat flour products. 



No. 


Sub- 
ject 
No. 


Kind of food. 


Protein. 


Fat 


Carbohy- 
drates. 


Energy. 


493 


2 
3 

1 

2 
3 

1 
2 
3 

1 
2 
3 


Macaroni and durum wheat flour bread 1:1 


P> r r< at. 
91.1 


96. l 
96. 1 


Per cent. 

- 

'.'7. 1 




494 

495 


do 

do 


91.2 
91.5 




92.8 


95. -6 


97.5 






Macaroni and durum wheat flour bread 2:1 




4% 


'.HI..". 


'.'7. 1 
96.0 


97.7 




497 
498 


do 

do 

Average of 3 experiments 






92.7 


96.6 


97.7 


91.9 




92. 8 


96.1 


97.6 


91.8 










88. 9 
92. 7 




97.5 

97. a 






do 






do 














90. -' 




97.3 






Average of all above experiments 

Durum wheat breakfast food with cream 

do 

da 






91.9 


96.1 


97.5 


91.5 




79.4 

BO :: 




•vs. 1 


85.1 








597 














80.9 






BS. 4 




Patent flour bread with milk.avei 








93.3 


95.6 


98. 1 











«U. S. Dept. Agr., Office of Experiment Stations Buhv B5, lul. 126, 148. 



75 

From Table 59 it will be seen that on an average 92.8 per cent 
of the protein of a ration of macaroni, bread made from durum wheat 
flour, and milk was digested and 91.8 per cent of the energy was 
available. As will be seen by reference to the table practically the 
same results were obtained when the ration contained large and 
small proportions of the bread made from durum wheat flour. With 
a ration of macaroni and milk the results obtained were very similar, 
90.2 per cent of the protein being digestible and 90.9 per cent of the 
energy available. Considering the average values for all the rations 
containing macaroni, 91.9 per cent of the protein was digestible and 
91.5 per cent of the energy available. The results obtained with a 
ration of durum wheat breakfast food and cream were lower, 80.9 per 
cent of the protein being digestible and 85.1 per cent of the energy 
available. 

Table 60 shows the calculated digestibility of the macaroni and 
durum wheat flour products alone, and for purposes of comparison the 
calculated digestibility of patent flour bread when forming part of a 
ration of bread and milk. The methods of calculating these results 
and the factors used have been explained on page 63. 

Table 60. — Digestibility of nutrients and availability of energy of macaroni and durum 
wheat flour products. 



Experi- 
ment 
No. 


Sub- 
ject 
No. 


Kind of food. 


Protein. 


Carbohy- 
drates. 


Energy. 




1 
2 
3 

1 
2 
3 

1 
2 
3 

1 
2 

3 




Per cent. 
89.8 
89.7 
86.3 


Per cent. 
98.4 
97.3 
96.6 


Per cent. 




do 




495 


do 












88.6 


97.4 










496 


87.5 
91.3 

83.7 


97.8 
97.4 
97.7 


93 5 


497 


do 




498 


do 












87.5 


97.6 


93 










88.1 


97.5 






Macaroni 

do 

do 




592 
593 
594 


S2.0 
88.9 
82.0 


97.3 
97.1 
97.0 


91.6 

91.7 
89.3 




84.3 


97.1 












86.8 


97.4 










595 


70.8 
76.1 
72.2 


88.5 
86.9 
89.9 


80 3 


596 


do 




597 


do 












73.0 


88.4 












88. i 


97.8 











On an average 88.1 per cent of the protein of macaroni and bread 
made from durum wheat flour was digested and 92. 7 per cent of the 
energy was available. Considering the above average values and 
the range in the results of the individual tests, it will be seen that 



76 

the presence of large or small proportions of bread made from durum 
wheat Hour had little effect on the digestibility of the total cereal 

food in the ration. This would indicate that the bread made from 
durum wheat flour had practically the same digestibility as the maca- 
roni — that is, that it made little difference a- regards digestibility 

whether the flour was made into a paste which was dried, boiled, 
and eaten or into a dough which was baked. In the tests in which 
macaroni was eaten without bread <>n an average B4.3 per cent of 
the protein was digested and 90.9 per cent of the energy available. 
Considering both range and average values, the figures obtained for 
macaroni alone agree quite closely with those obtained for macaroni 
plus durum wheat flour bread. When all the ration- containing 
macaroni are taken into account it is found that on an average 86.8 
per cent of the protein was digestible and 92.1 per cent of the 
energy available. Somewhat lower results were obtained with the 
durum wheat breakfast food than with the macaroni made from 
the same lot of wheat, the coefficient of the digestibility of protein 
being 73.0 per cent and the coefficient of availability of energy 80.6 
per cent. 

As will be seen by Table 60 the results obtained with macaroni differ 
little from the average values obtained with bread made from straight- 
grade flour. 

As to the cost of nutrients of bread and macaroni, price- differ in 
different localities and at different times to sucb an extent that only 
general comparisons are possible. A pound of dry macaroni retailing 
for 10 cents contains approximately the same amount of nutrients 
as are present in 1.3 to 1.1 pounds of bread costing from »', to 1" 
cents, the difference in nutritive value per pound of the two mate 
rials being due largely to a difference in water content. In other 
words, macaroni furnishes, pound for pound, somewhat more nutri- 
tive material than bread but at a higher cost. The use of macaroni in 
the diet is a matter which depends quite largely upon food habit- and 
the relative cost of materials. In Italy, as is well known, thi- food i- 
much more commonly used than in the United State-. The results of 
dietary studies made in Chicago" confirms the belief that after immi- 
gration to this country the Italians retain in large measure their f 1 

habits, and macaroni is still a very important article of diet, replacing 
bread and other common cereal foods to a considerable extent. Ma. a- 
roni and similar Italian pastes are favorite article-, of diet in many 
American families. The experimental and other evidence available 
confirms the opinion that the Italian pastes are digestible and nutri- 
tious articles of diet, but that at ordinary price- bread i> a somewhat 
cheaper source of nutrient-. The u-e of macaroni i-. however, desir- 
able because of the variety which it introduce- into the menu and the 

«U. S. Dept. Agr., Office of Experiment stati.-n> Bui. 55. 



77 

possibility it affords of making- satisfactory combinations with other 
food materials. 

As regards the use of durum wheat for making breakfast foods, the 
experiments reported herewith show that it is possible to produce 
goods which in composition and digestibility compare favorably with 
whole-wheat flour. The superior digestibility of the macaroni and 
bread is probably due to the fact that the ground grain from which 
these products are made offers a better opportunity- for the action of 
the digestive juices than the flaked kernels of the breakfast food. 

THE RESULTS OF AMERICAN AND OTHER EXPERIMENTS WITH 
MACARONI. 

As noted on another page (p. 55), Rubner, Jacoangeli and Bonanni, 
and Cappelletti have studied the digestibility of macaroni and similar 
products, and it is interesting to compare the results of their experi- 
ments with those obtained in the investigations carried on at the Min- 
nesota Experiment Station. The earliest of these experiments are those 
made by Rubner with a healthy man who lived exclusively on the mate- 
rials studied. In the macaroni tests these were macaroni noodles made 
with and without the addition of wheat gluten. In one of the tests 
" Spaetzels," a sort of flour paste poured through a sieve into boiling 
water and quickly cooked, constituted the entire ration. When cooked 
this material seems comparable with macaroni or similar foods, though 
of course it is unlike them as regards method of preparation. 

In connection with an investigation of the value of Indian corn, alone 
or with wheat, for making alimentary pastes, Jacoangeli and Bonanni 
studied the digestibility of macaroni made from wheat, as well as that 
of pastes from corn and corn and wheat, and also of corn-meal mush, 
such as is commonly eaten in Italy, i. e., polenta. The subject of the 
experiments was a healthy man. In the test with macaroni and other 
pastes these foods constituted the entire diet, being eaten in the 
form of soup. In all the tests two meals were taken each day, one at 
10 o'clock in the morning and the other at 4 o'clock in the afternoon. 
So far as can be learned, the studies of the value of Indian corn for 
use in the manufacture of alimentary pastes, though undertaken upon 
a comparatively large scale, never passed the experimental stage. 

Using three men as subjects, Cappelletti studied the digestibility of 
macaroni or a similar Italian paste, rice and " sitos," a sort of break- 
fast food made from a Sardinian variety of durum wheat by splitting 
the grain lengthwise and removing the outer layer. The foods were 
eaten in the form of thick soup. 

The following table summarizes the results obtained by these inves- 
tigators as well as the average results obtained at the Minnesota 
Experiment Station. In the case of the experiments cited for com- 



78 



parison, data regarding the coefficients of the availability of energy were 
not reported nor could these values becalculated from the experimental 
data included in the original publications. 

Table 61. — Summery of American <iiul other experiments on th* digestibility of macaroni. 



Kind of food. 



Macaroni noodles ( Riibnen 

Macaroni Doodles with wheat gluten (Rubner) — 

Spaetzels ( Rubner I 

Macaroni made from best quality wheat flour 

(Jacoangeli and Bonanni) 

Macaroni made from low-grade Hour (Jacoangeli 

and Bonanni ) 

Macaroni (Cappelletti) 

Durum wheat breakfast i" 1 . Capi.clletti) 

Macaroni with durum wheat flourbread (8nyder 

Macaroni (Snyder) 

Durum wheat breakfast food ( Snyder ) 



mauV, I ' r " t ' i "- 



™- r ;i«^ 



Percent Percent. 

■ 

94.8 88.8 98.0 97.7 

79.8 



%.l 
94.8 



91.2 

- 

7- 7 


-7 D 


84.3 



96.3 

'.'7. -J 
96. 1 

88.4 



80.6 



It will l>e seen from the figures in the above table that the results 
obtained with macaroni in the experiments at the Minnesota Experi- 
ment Station agree quite closely with those obtained by the European 
investigators quoted. In other words, the American -grown durum 
wheat produced macaroni which was equal in this respect to that made 
from European wheats. When it is remembered that the American 
macaroni is of excellent quality, and in appearance, flavor, and compo- 
sition verj' like the standard European products, the conclusion seems 
warranted that in all important respects the American material i- 
equal to the European. As previously noted, the breakfast food 
tested at the Minnesota Experiment Station had somewhat lower 
coefficients of digestibility than the macaroni made from the same lot 
of wheat, and it is interesting to note that Cappelletti also found that 
the durum wheat breakfast food contained somewhat lower propor- 
tions of digestible nutrients than the macaroni. The published data at 
present available regarding the average coefficients of breakfast foods 
from ordinary varieties of wheat are too limited for satisfactory com- 
parisons, but it seems probable that durum wheat breakfast food- 
compare favorably with other wheats in this respect. 



INCOME AND OUTGO OF NITROGEN. 

In connection with the digestion experiments with macaroni and 
durum wheat breakfast food the income and outgo of nitrogen was 
determined. The data of this character for the individual experi- 
ments is summarized in Table 62: 



T\ble 62. — Average daUy income and outqo of nitrogen in digestion experiments No, 
493-498, 592-597. 





Sub- 
ject 
No. 


Kind of food. 






Nitrogen. 




Experi- 
ment 
No. 


In food. 


■»— ■ 


In feces. 


Gain ( + ) 
loss (-). 


493 


l 

3 

1 

2 
3 

1 
2 
3 

1 
2 
3 


Macaroni and durum wheat 


flour bread 1:1 


Grams. 
16.51 
21.44 

15. 24 

20.33 
22. 93 

16. 92 
42.33 
51.85 
48.58 
28.43 
37.03 
44.95 


Grams. 

17.62 
18.41 
14.78 

17. 35 
19.97 
17.30 
16.84 
45. 91 
59.03 
32.92 
47. 85 
43.31 


Grams. 
1.02 
1.39 
1.62 

1.38 
1.26 

4^67 
3.80 
5.28 
5.87 
6.33 
8.88 


Grams. 
-2.13 


494 
495 
496 






+1.64 






+1.84 


Macaroni and durum wheat 


flour bread 2:1 


+1.60 


497 
498 
592 
593 
594 
595 
5% 
597 






+1.70 


do 

Macaroni with milk 




-2.00 
+ 5.21 

+ .54 








Durum wheat breakfast food 


with cream 


-2.59 

-4.29 


do 




-1.81 



In six of the experiments there was an average daily gain of nitro- 
gen and in an equal number there was a loss. As was noted in the 
discussion of data regarding the income and outgo of nitrogen in 
experiments with different sorts of bread reported earlier in this bul- 
letin (p. 52), it is probable that in every case nitrogen equilibrium 
would have been reached if the experimental periods had been longer. 
On an average the proportion of nitrogen excreted in the feces was 
greater with the durum wheat breakfast food, i. e., with the coarser 
product, than with the macaroni, as might be inferred from the some- 
what lower digestibility of the breakfast cereal referred to in the dis- 
cussion of the digestion experiments. In general, no differences in the 
nitrogen balance were observed which could be attributed to the durum 
wheat products consumed. 



CONCLUSIONS OF EXPERIMENTS WITH MACARONI. 

In these investigations two samples of durum wheat grown in North 
Dakota were milled with an experimental mill at the Minnesota Experi- 
ment Station and the product obtained was made into macaroni, which 
was used for digestion experiments with healthy young men engaged 
in a fair amount of muscular work as subjects. It was found that 
when the offals from the durum wheat were remilled the total } T ield of 
flour from durum wheat was approximately the same as from ordinary 
wheats, but that the different grades of flour were obtained in somewhat 
different proportions. The durum wheat was somewhat harder to 
reduce and required more power in milling than ordinary wheat. The 
manufacture of semolina from durum wheat requires somewhat differ- 
ent tempering, granulation, and bolting than are required in the manu- 
facture of flour for bread-making purposes from ordinary wheat. In 
the manufacture of macaroni the semolina or coarse flour undergoes 



80 

botli physical and chemical changes. Water is removed in drying the 
macaroni and the starch and gluten apparently undergo a slight hydra- 
tion. When macaroni is cooked in water about 2.25 percent of the 
soluble matters present are extracted, which suggests that as little 
water as possible should be used in cooking the macaroni when Btricl 
economy is desirable. 

As shown by experiments with healthy men, macaroni has approxi- 
mately the same digestibility and supplies about the same am. unit of 
nutrients, pound for pound on a dry-matter basis, as bread made from 
straight-grade flour. Consuming either large or small amounts of 
bread made from durum wheat flour with the macaroni exercised no 
appreciable effect upon the digestibility of the nutrients and the availa- 
bility of the energy present. 

.Macaroni is a highly digestible and nutritious article of diet, cor- 
responding in these respects quite closely to bread, though at ordinary 
prices it furnishes nutrients at a somewhat greater cost than bread; 
nevertheless, it may he fairly considered an economical article of diet. 
Macaroni may be readily combined with other food material- and thus 
may he used to give variety to the diet. 

The durum wheat breakfast food resembled quite closely in compo- 
sition the macaroni made from similar wheat. It was not quite a- 
thoroughly digested, though it- digestibility was fairly high a- com- 
pared with many vegetable food-. The observed differences in dij 
ibility of the breakfast food and the Hour product- are undoubtedly 
due to methods of manufacture, the flour product- being rather finely 
ground and therefore in a condition favorable for the action of the 
digestive juices. 

Taken as a whole the tests -how that these American-made macaronies 
were directly comparable with standard-made goods of European 
manufacture. 

The general summary of results and conclusions on the digestibility 
and nutritive value of bread is given on page- .">:'. ami 54 of this 
bulletin. 



LB Mr 



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